Change char->free to auto_char char for autocleanup

Replace `gchar` and `g_free` to `auto_gchar`
Correct certain  `char` functions/variables to `gchar`

Related to #1819.

Edited by @jubalh.

src/tools/http_upload.c

@@ -163,7 +163,7 @@ http_file_put(void* userdata)
 
     FILE* fh = NULL;
 
-    char* err = NULL;
+    auto_char char* err = NULL;
     gchar* content_type_header;
     // Optional headers
     gchar* auth_header = NULL;
@@ -318,7 +318,6 @@ http_file_put(void* userdata)
         }
         cons_show_error(msg);
         g_free(msg);
-        free(err);
     } else {
         if (!upload->cancel) {
             msg = g_strdup_printf("Uploading '%s': 100%%", upload->filename);