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/xmpp/capabilities.c

@@ -58,7 +58,7 @@
 #include "xmpp/form.h"
 #include "xmpp/capabilities.h"
 
-static char* cache_loc;
+static gchar* cache_loc;
 static GKeyFile* cache;
 
 static GHashTable* jid_to_ver;
@@ -355,7 +355,7 @@ caps_close(void)
     cache = NULL;
     g_hash_table_destroy(jid_to_ver);
     g_hash_table_destroy(jid_to_caps);
-    free(cache_loc);
+    g_free(cache_loc);
     cache_loc = NULL;
     g_hash_table_destroy(prof_features);
     prof_features = NULL;