build: improve version.h generation

Move version.h generation into lib/Makefile.sources so that it can be
shared between the Autotools and Android build systems. Also make sure the
"updating version.h" message is only displayed when version.h actually
changes and remove unnecessary includes of version.h.

This also includes changes from Tvrtko Ursulin to prevent a build from
within the git repository failing when git is not available.

Signed-off-by: Thomas Wood <thomas.wood@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
8 files changed