compat: don't build when strlcpy is present

[alebcay]

In environments where strlcpy is present, an attempt will be made to build libcompat.la, but libcompat will have no sources because of the conditional in compat/Makefile.am. As such the build will fail because ar is trying to create an archive without any sources passed to it.

Instead, move the conditional check to the top-level Makefile.am, such that strlcpy.lo is not built and also libcompat.la is ignored entirely.

[job]

thanks!