Add check program "git-check-racy"

This will help counting the racily clean paths, but it should be
useless for daily use.  Do not even enable it in the makefile.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/Makefile b/Makefile
index b86de76..04ed84d 100644
--- a/Makefile
+++ b/Makefile
@@ -194,7 +194,11 @@
 	git-update-server-info$X \
 	git-upload-pack$X git-verify-pack$X \
 	git-pack-redundant$X git-var$X \
-	git-describe$X git-merge-tree$X git-blame$X git-imap-send$X
+	git-describe$X git-merge-tree$X git-blame$X git-imap-send$X \
+	$(EXTRA_PROGRAMS)
+
+# Empty...
+EXTRA_PROGRAMS =
 
 BUILT_INS = \
 	git-format-patch$X git-show$X git-whatchanged$X \