kbuild: support mercurial in setlocalversion

This represents mercurial changesets similarly to git. For untagged
revisions, append the changeset id. If there are uncommitted changes,
append -dirty. For example, -hgc60016ba6237-dirty

Signed-off-by: Aron Griffis <[e-mail]>
Signed-off-by: Sam Ravnborg <[e-mail]>

scripts/setlocalversion

···
 	if git diff-index HEAD | read dummy; then
 		printf '%s' -dirty
 	fi
+
+	# All done with git
+	exit
+fi
+
+# Check for mercurial and a mercurial repo.
+if hgid=`hg id 2>/dev/null`; then
+	tag=`printf '%s' "$hgid" | cut -d' ' -f2`
+
+	# Do we have an untagged version?
+	if [ -z "$tag" -o "$tag" = tip ]; then
+		id=`printf '%s' "$hgid" | sed 's/[+ ].*//'`
+		printf '%s%s' -hg "$id"
+	fi
+
+	# Are there uncommitted changes?
+	# These are represented by + after the changeset id.
+	case "$hgid" in
+		*+|*+\ *) printf '%s' -dirty ;;
+	esac
+
+	# All done with mercurial
+	exit
 fi