tools/setlocalversion: use a git-describe-ish format

Change the automatic local version to have the form -nnnnn-gSHA1SUMID,
where 'nnnnn' is the number of commits since the last tag (i.e.,
1.3.2-rc3).  This makes it much easier to recognize "newer" versions
and to see how much has been changed since the referenced tag.

Stolen from Linux kernel's scripts/setlocalversio, see commit d882421f.

Signed-off-by: Wolfgang Denk <wd@denx.de>

tools/setlocalversion

@@ -11,12 +11,15 @@ cd "${1:-.}" || usage
 # Check for git and a git repo.
 if head=`git rev-parse --verify HEAD 2>/dev/null`; then
 	# Do we have an untagged version?
-	if  [ "`git name-rev --tags HEAD`" = "HEAD undefined" ]; then
-		printf '%s%s' -g `echo "$head" | cut -c1-8`
+	if git name-rev --tags HEAD | \
+	   grep -E '^HEAD[[:space:]]+(.*~[0-9]*|undefined)$' > /dev/null; then
+	        git describe | awk -F- '{printf("-%05d-%s", $(NF-1),$(NF))}'
 	fi
 
 	# Are there uncommitted changes?
-	if git diff-files | read dummy; then
+	git update-index --refresh --unmerged > /dev/null
+	if git diff-index --name-only HEAD | grep -v "^scripts/package" \
+	    | read dummy; then
 		printf '%s' -dirty
 	fi
 fi