build system: Only setup git hooks if we're in a git checkout

A bit crude test, but before we would have _created_ .git
and confused later git presence tests.

Change-Id: Iec882d0e38ce1bd227cae8c1e541fb21be085290
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: http://review.coreboot.org/8601
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
1 file changed