Set PKG_CONFIG_LIBDIR in autobuild.sh

If PKG_CONFIG_LIBDIR is not set when doing mingw32/64 builds,
then pkg-config may silently fallback to native versions of
libraries, with predictably bad results. Setting PKG_CONFIG_LIBDIR
forces it to only consider the mingw32/64 libraries.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

autobuild.sh

@@ -69,6 +69,7 @@ fi
 if test -x /usr/bin/i686-w64-mingw32-gcc ; then
   make distclean
 
+  PKG_CONFIG_LIBDIR="/usr/i686-w64-mingw32/sys-root/mingw/lib/pkgconfig:/usr/i686-w64-mingw32/sys-root/mingw/share/pkgconfig" \
   PKG_CONFIG_PATH="$AUTOBUILD_INSTALL_ROOT/i686-w64-mingw32/sys-root/mingw/lib/pkgconfig" \
   CC="i686-w64-mingw32-gcc" \
   ../configure \
@@ -88,6 +89,7 @@ fi
 if test -x /usr/bin/x86_64-w64-mingw32-gcc ; then
   make distclean
 
+  PKG_CONFIG_LIBDIR="/usr/x86_64-w64-mingw32/sys-root/mingw/lib/pkgconfig:/usr/x86_64-w64-mingw32/sys-root/mingw/share/pkgconfig" \
   PKG_CONFIG_PATH="$AUTOBUILD_INSTALL_ROOT/x86_64-w64-mingw32/sys-root/mingw/lib/pkgconfig" \
   CC="x86_64-w64-mingw32-gcc" \
   ../configure \