pkg-config: tailor libass.pc for static-only builds

Add library and package dependencies to the default (non-private)
pkg-config fields for static-only builds. This makes sure the packages
and libraries are always picked up and used, even if the --static option
is not supplied to the pkg-config commandline.

configure.ac

@@ -93,7 +93,8 @@ fi
 
 AM_CONDITIONAL([HAVE_LIBPNG], [test x$libpng = xtrue])
 
-# Add dependent libraries to pkg-config for static linking
+# add libraries/packages to pkg-config for static linking
+PKG_LIBS="-lm"
 PKG_REQUIRES="freetype2 >= 9.6.3"
 PKG_REQUIRES="fribidi >= 0.19.0, ${PKG_REQUIRES}"
 if test x$enca = xtrue; then
@@ -105,7 +106,11 @@ fi
 if test x$harfbuzz = xtrue; then
     PKG_REQUIRES="harfbuzz >= 0.7.0, ${PKG_REQUIRES}"
 fi
-AC_SUBST([PKG_REQUIRES])
+
+AC_SUBST([PKG_LIBS_DEFAULT], [$(test x$enable_shared = xno && echo $PKG_LIBS)])
+AC_SUBST([PKG_REQUIRES_DEFAULT], [$(test x$enable_shared = xno && echo $PKG_REQUIRES)])
+AC_SUBST([PKG_LIBS_PRIVATE], [$(test x$enable_shared = xno || echo $PKG_LIBS)])
+AC_SUBST([PKG_REQUIRES_PRIVATE], [$(test x$enable_shared = xno || echo $PKG_REQUIRES)])
 
 # Setup output beautifier.
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])

libass.pc.in

@@ -6,7 +6,8 @@ includedir=@includedir@
 Name: libass
 Description: LibASS is an SSA/ASS subtitles rendering library
 Version: @PACKAGE_VERSION@
-Requires.private: @PKG_REQUIRES@
-Libs: -L${libdir} -lass
-Libs.private: -lm
+Requires: @PKG_REQUIRES_DEFAULT@
+Requires.private: @PKG_REQUIRES_PRIVATE@
+Libs: -L${libdir} -lass @PKG_LIBS_DEFAULT@
+Libs.private: @PKG_LIBS_PRIVATE@
 Cflags: -I${includedir}