Revert "Pass --always to 'git describe'."

This reverts commit 8638d78c.
Since it doesn't actually fix the original problem with shallow clones,
it returns just a hash, not something we (currently) can extract as a
version string in the form things are expecting.  Which means the .pc
version checks for things using the library at least will still fail.

update_version

@@ -34,8 +34,7 @@ fi
 # -dirty from files that have been touched but are not actually altered in the
 # working dir.
 GIT_VERSION=$(cd "$SRCDIR" && git status > /dev/null 2>&1 \
-                           && git describe --tags --match 'v*' \
-                                           --always --dirty 2> /dev/null)
+                           && git describe --tags --match 'v*' --dirty 2> /dev/null)
 GIT_VERSION=${GIT_VERSION#v}
 
 if [ -n "$GIT_VERSION" ]; then