fix GCArgs load from ini (#7156) (#7157)

Author: lunny

modules/setting/git.go

@@ -20,7 +20,7 @@ var (
 		MaxGitDiffLines          int
 		MaxGitDiffLineCharacters int
 		MaxGitDiffFiles          int
-		GCArgs                   []string `delim:" "`
+		GCArgs                   []string `ini:"GC_ARGS" delim:" "`
 		Timeout                  struct {
 			Default int
 			Migrate int