Just for the record, I was having issues getting /usr/include/gsm.h or
/usr/lib64/libgsm.a to show up after a successful build/install of gsm-1.0.12.
After playing around with the makefile by hand I realized the project doesn't
create the target install directories itself, hence the need for "dodir blah
blah" to make the target dirs show up in /var/tmp/portage/.../image.
The catch here is that in src_install() we're using
GSM_INSTALL_LIB="${D}"/usr/$(get_libdir) however the dodir statically defines
the lib dir in the image folder to be /usr/lib. In the case of amd64 this will
obviously fail.
Changing /usr/lib to /usr/$(get_libdir) in the dodir line of the ebuild fixes
this issue for me
~jtriley