Provide the ability for -portable to continue to compile, until such time that gotd and gotsh have been enabled in -portable.

Allow for warnings via AM_CFLAGS in a common Makefile, and let those values propagate to all other Makefiles. Currently the more useful checks are disabled until upstream changes are made to reduce warnings. While here, also fix the version string to remove quotes.

libexec is a common path which is understood by autotools, and should be honoured. Patch from Christian "naddy" Weisgerber

This adds the capability to compile got-portable on FreeBSD.

The got_lib_privsep.h header expects the path to the libexec directory to be called GOT_LIBEXECDIR. At the moment it always falls back to using /usr/libexec. Fix what looks to be a typo.

This commit modifies the GoT main branch to be able to compile it under linux.