Warnings in libvorbis/libvorbisfile

The attached patch against SVN r18145 corrects a number of compiler warnings with "gcc -Wall -Wempty-body -Wmissing-declarations -Wpointer-arith -Wsign-compare -Wstrict-prototypes" on GCC 4.6.1:

• Adds a new header lib/block.h to hold the declaration of vorbis_window(), #includes it in block.c and vorbisfile.c, and removes the declaration of that function from vorbisfile.c.

• Adds "static" to internal functions which don't have it: res[012]_*() in res012.c and _make_words() and run_test() in sharedbook.c.

• Changes () to (void) in function definitions so they are proper prototypes: main() (for tests) in sharedbook.c and host_is_big_endian() in vorbisfile.c.

• Deletes the unused function _vi_gpsy_free() from psy.c.

• Deletes the unused variable lastdelta from Laguerre_With_Deflation() in lsp.c.

• Propagates "const" up from the vwin64/vwin128 arrays in window.c through _vorbis_window_get() to its callers (and onward).

• Fixes a constant in info.c which was one digit too long (0x7ffffffff).

I can split this out into separate patches if desired, but I've bundled the changes together since they don't change any functionality.