style: fixed one line's indentation.

Author: agentzh

src/ngx_http_lua_regex.c

@@ -1603,8 +1603,8 @@ ngx_http_lua_ngx_re_sub_helper(lua_State *L, unsigned global)
 
 #else /* LUA_HAVE_PCRE_DFA */
 
-        msg = "at least pcre 6.0 is required for the DFA mode";
-        goto error;
+            msg = "at least pcre 6.0 is required for the DFA mode";
+            goto error;
 
 #endif /* LUA_HAVE_PCRE_DFA */