emacs のビルド中に以下のエラー


configure:8165: error: Package libpng12 was not found in the pkg-config search path.
Perhaps you should add the directory containing `libpng12.pc'
to the PKG_CONFIG_PATH environment variable
Package 'libpng12', required by 'cairo', not found


以下に回避策発見。
http://forums.gentoo.org/viewtopic-p-6396532.htm

 /usr/sbin/libpng-1.4.x-update.sh 
 emerge -1 cairo 
 revdep-rebuild --library libpng12.so.0