deprecate core.statinfo at Git 2.0 boundary

c08e4d5b (Enable minimal stat checking, 2013-01-22) advertised
the configuration variable core.checkstat in the documentation and
its log message, but the code expected core.statinfo instead.

For now, add core.checkstat, and warn people who have core.statinfo
in their configuration file that we will remove it in Git 2.0.
Noticed-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

config.c

@@ -566,7 +566,20 @@ static int git_default_core_config(const char *var, const char *value)
 		trust_ctime = git_config_bool(var, value);
 		return 0;
 	}
-	if (!strcmp(var, "core.statinfo")) {
+	if (!strcmp(var, "core.statinfo") ||
+	    !strcmp(var, "core.checkstat")) {
+		/*
+		 * NEEDSWORK: statinfo was a typo in v1.8.2 that has
+		 * never been advertised.  we will remove it at Git
+		 * 2.0 boundary.
+		 */
+		if (!strcmp(var, "core.statinfo")) {
+			static int warned;
+			if (!warned++) {
+				warning("'core.statinfo' will be removed in Git 2.0; "
+					"use 'core.checkstat' instead.");
+			}
+		}
 		if (!strcasecmp(value, "default"))
 			check_stat = 1;
 		else if (!strcasecmp(value, "minimal"))