Move win32 package build details to mingw/README.md

In theory `mingw/Makefile` can build a binary release, but
it doensn't quite works and omits some niceties, so we still
need the detailed build instructions to compare with.

However, the details aren't relevent to the general release
checklist, so pretend `make -C ming package` works at that
level.

Also convert the mingw README to markdown for better
display on hosting sites.

doc/release.txt

@@ -39,41 +39,11 @@ Win32 binaries:
   - Downloads versions of libogg, opus, openssl.
   - Compiles them.
   - Compiles static opusfile and examples against the built deps.
-- Compile dynamic opusfile with:
-  - ./configure --host=i686-w64-mingw32 --prefix=/path/to/builddir/mingw \
-        PKG_CONFIG_PATH=/path/to/builddir/mingw/lib/pkgconfig
-  - make && make check && make -C doc/latex
-    - If Doxygen fails because of unescaped '#' characters in URLs
-      Update to at least Doxygen 1.8.15. Doxygen 1.8.3 also works.
-- mkdir opusfile-${version}-win32
-- Copy AUTHORS COPYING README.md include/opusfile.h to the release dir.
-  - Don't put opusfile.h in an opusfile-${version}-win32/include directory,
-    just put it straight in the release dir.
+- run `make -C mingw package`
+  - Creates an opusfile-${version}-win32.zip binary package.
 - Merge changes between README.md and the version in the last
   binary release. E.g. it's good to include versions of the dependencies,
   release notes, etc.
-- Convert README.md to DOS line endings.
-- Copy .libs/libopusfile-0.dll to the release dir.
-- Copy .libs/libopusfile.a to the release dir.
-- Copy .libs/libopusfile.dll.a to the release dir. (May not be needed?)
-- Copy .libs/libopusurl-0.dll to the release dir.
-- Copy .libs/libopusurl.a to the release dir.
-- Copy .libs/libopusurl.dll.a to the release dir. (May not be needed?)
-- Copy mingw/bin/*.dll to the release dir for dependencies.
-- Copy any other dependent dlls, e.g. on Fedora 23 I needed to copy
-    /usr/i686-w64-mingw32/sys-root/mingw/bin/libgcc_s_sjlj-1.dll
-    /usr/i686-w64-mingw32/sys-root/mingw/bin/libwinpthread-1.dll
-  On Gentoo I needed to copy
-    /usr/lib64/gcc/i686-w64-mingw32/7.3.0/libgcc_s_sjlj-1.dll
-  TODO: It may be possible to avoid this with CFLAGS="-static-libgcc"
-- Copy doc/latex/refman.pdf to opusfile-${version}-win32/opusfile-${version}.pdf
-- Copy examples/.libs/*.exe to the release dir.
-- Run "i686-w64-ming32-strip *.dll *.a *.exe" in the release dir.
-- In the release dir, run:
-    sha256sum * > SHA256SUMS.txt
-    gpg --detach-sign --armor SHA256SUMS.txt
-- In the parent directory, create the archive:
-    zip -r opusfile-${version}-win32.zip opusfile-${version}-win32/*
 - Copy the archive to a clean system and verify the examples work
   to make sure you've included all the necessary libraries.
 - Upload the archive zipfile to websites.

mingw/README.md

+# Cross-compiling under mingw
+
+Just running `make` in this directory should download
+and build opusfile and its dependencies. Some mingw
+libraries need to be compiled into the final package.
+
+## Generic instructions
+
+To build opusfile under mingw, you need to first build:
+
+- libogg
+- libopus
+- openssl
+
+For 'make check' to work, you may need wine installed.
+
+To build openssl, try:
+
+ CROSS_COMPILE="i686-w64-mingw32-" ./Configure mingw no-asm no-shared --prefix=$PWD/mingw && make depend && make -j8 && make install
+
+To build opusfile, try:
+
+ CC=i686-w64-mingw32-gcc PKG_CONFIG_PATH=$PWD/lib/pkgconfig RANLIB=i686-w64-mingw32-ranlib make -f ../unix/Makefile
+
+## Building the release package
+
+Running `make package` should produce a binary package.
+
+The steps are something like
+
+- Compile dynamic opusfile with:
+  - ./configure --host=i686-w64-mingw32 --prefix=/path/to/builddir/mingw \
+        PKG_CONFIG_PATH=/path/to/builddir/mingw/lib/pkgconfig
+  - make && make check && make -C doc/latex
+    - If Doxygen fails because of unescaped '#' characters in URLs
+      Update to at least Doxygen 1.8.15. Doxygen 1.8.3 also works.
+- mkdir opusfile-${version}-win32
+- Copy AUTHORS COPYING README.md include/opusfile.h to the release dir.
+  - Don't put opusfile.h in an opusfile-${version}-win32/include directory,
+    just put it straight in the release dir.
+- Merge changes between README.md and the version in the last
+  binary release. E.g. it's good to include versions of the dependencies,
+  release notes, etc.
+- Convert README.md to DOS line endings.
+- Copy .libs/libopusfile-0.dll to the release dir.
+- Copy .libs/libopusfile.a to the release dir.
+- Copy .libs/libopusfile.dll.a to the release dir. (May not be needed?)
+- Copy .libs/libopusurl-0.dll to the release dir.
+- Copy .libs/libopusurl.a to the release dir.
+- Copy .libs/libopusurl.dll.a to the release dir. (May not be needed?)
+- Copy mingw/bin/*.dll to the release dir for dependencies.
+- Copy any other dependent dlls, e.g. on Fedora 23 I needed to copy
+    /usr/i686-w64-mingw32/sys-root/mingw/bin/libgcc_s_sjlj-1.dll
+    /usr/i686-w64-mingw32/sys-root/mingw/bin/libwinpthread-1.dll
+  On Gentoo I needed to copy
+    /usr/lib64/gcc/i686-w64-mingw32/7.3.0/libgcc_s_sjlj-1.dll
+  TODO: It may be possible to avoid this with CFLAGS="-static-libgcc"
+- Copy doc/latex/refman.pdf to opusfile-${version}-win32/opusfile-${version}.pdf
+- Copy examples/.libs/*.exe to the release dir.
+- Run "i686-w64-ming32-strip *.dll *.a *.exe" in the release dir.
+- In the release dir, run:
+    sha256sum * > SHA256SUMS.txt
+    gpg --detach-sign --armor SHA256SUMS.txt
+- In the parent directory, create the archive:
+    zip -r opusfile-${version}-win32.zip opusfile-${version}-win32/*
+- Copy the archive to a clean system and verify the examples work
+  to make sure you've included all the necessary libraries.
+

mingw/README.mingw

-= Cross-compiling under mingw =
-
-Just running 'make' in this directory should download
-and build opusfile and its dependencies. Some mingw
-libraries need to be compiled into the final package.
-
-== Generic instructions ==
-
-To build opusfile under mingw, you need to first build:
-
-libogg
-libopus
-openssl
-
-For 'make check' to work, you may need wine installed.
-
-To build openssl, try:
-
- CROSS_COMPILE="i686-w64-mingw32-" ./Configure mingw no-asm no-shared --prefix=$PWD/mingw && make depend && make -j8 && make install
-
-To build opusfile, try:
-
- CC=i686-w64-mingw32-gcc PKG_CONFIG_PATH=$PWD/lib/pkgconfig RANLIB=i686-w64-mingw32-ranlib make -f ../unix/Makefile