libxpm have library but no .pc pkgconfig file on SDK #319
Description
On GIMP project we are starting to develop our official snap to further publishing on Snap Store.
But at build time on snapcraft we are needing to list libxpm-dev on build-packages: because there is no pkgconfig file on the SDK
So, we should either remove libxpm .so libraries from the SDK (since it is pretty niche, apt rdepends shows that no GNOME library depends on it) or ship the .pc files to help some projects like GIMP that use such dep so build easily without needing to install libxpm-dev.