libgpg-error: add pkg-config support

using yocto's patch from:
http://git.yoctoproject.org/cgit/cgit.cgi/poky/tree/meta/recipes-support/libgpg-error/libgpg-error-1.12/pkgconfig.patch

Signed-off-by: Alejandro Mery <amery@geeks.cl>