use xstrdup please

We generally prefer xstrdup to just plain strdup.
Make it so.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

config.c

@@ -351,12 +351,12 @@ int git_default_config(const char *var, const char *value)
 	}
 
 	if (!strcmp(var, "i18n.commitencoding")) {
-		git_commit_encoding = strdup(value);
+		git_commit_encoding = xstrdup(value);
 		return 0;
 	}
 
 	if (!strcmp(var, "i18n.logoutputencoding")) {
-		git_log_output_encoding = strdup(value);
+		git_log_output_encoding = xstrdup(value);
 		return 0;
 	}