make_version: Use 'git rev-parse' if only looking for a sha5.

Different versions of git have variability in how the log output looks.
Instead of git log, we can use git rev-parse directly.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>

Origin: http://svnview.digium.com/svn/dahdi?view=rev&rev=9475

git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/branches/2.4@9760 a0bf4364-ded3-4de4-8d8a-66a801d63aff

build_tools/make_version

@@ -66,7 +66,7 @@ elif [ -d ${1}/.git ]; then
             fi
             # Some older versions of git do not support all the above
             # options.
-            VERSION=GIT-`git log --abbrev-commit -1 --pretty=oneline --abbrev=7 | cut -f 1 -d .`${MODIFIED}
+            VERSION=GIT-`git rev-parse --short --verify HEAD`${MODIFIED}
         fi
         echo ${VERSION}
     else