build: only use the git version on install, not in the build tree

build: only use the git version on install, not in the build tree

having the git version in our version.h in the build tree is annoying
for developers, as every time you commit or rebase you need to spend
several minutes re-linking. This changes it to use the git version
only on install, which is much more useful as when you actually
install the binaries you may be using them in a way that reporting the
version is useful

Pair-Programmed-With: Andrew Bartlett <abartlet@samba.org>

Autobuild-User: Andrew Tridgell <tridge@samba.org>
Autobuild-Date: Fri Jun 17 08:37:06 CEST 2011 on sn-devel-104