qemu-malloc.c: Remove qemu-specific heap routines.

Remove all uses of qemu_malloc/malloc0/realloc/free/strdup/etc to use
the equivalent GLib functions (g_malloc, g_free, ...) as per upstream.

This also removes qemu-malloc.c since it's no longer required.

Change-Id: I3c36a0396b73dd114b8da385b43f56a2e54dbb15
diff --git a/bt-vhci.c b/bt-vhci.c
index b6b670f..c0e1d5c 100644
--- a/bt-vhci.c
+++ b/bt-vhci.c
@@ -156,7 +156,7 @@
         exit(-1);
     }
 
-    s = qemu_mallocz(sizeof(struct bt_vhci_s));
+    s = g_malloc0(sizeof(struct bt_vhci_s));
     s->fd = fd;
     s->info = info ?: qemu_next_hci();
     s->info->opaque = s;