In pkg-config files, libraries not exposed through the library, but just needed

during static linking should be listed under Libs.private, not Libs.
patch by Anssi Hannula, anssi.hannula gmail com

Originally committed as revision 13067 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -2145,7 +2145,8 @@ Description: $comment
 Version: $version
 Requires: $requires
 Conflicts:
-Libs: -L\${libdir} -l${shortname} $libs
+Libs: -L\${libdir} -l${shortname}
+Libs.private: $libs
 Cflags: -I\${includedir}
 EOF
 cat <<EOF >$name-uninstalled.pc
@@ -2159,7 +2160,8 @@ Description: $comment
 Version: $version
 Requires: $requires
 Conflicts:
-Libs: \${libdir}/${LIBPREF}${shortname}${LIBSUF} $libs
+Libs: \${libdir}/${LIBPREF}${shortname}${LIBSUF}
+Libs.private: $libs
 Cflags: -I\${includedir}
 EOF
 }