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/tap-win32.c b/tap-win32.c
index af20674..734ad59 100644
--- a/tap-win32.c
+++ b/tap-win32.c
@@ -641,7 +641,7 @@
     /* FIXME: need to kill thread and close file handle:
        tap_win32_close(s);
     */
-    qemu_free(s);
+    g_free(s);
 }
 
 static ssize_t tap_receive(VLANClientState *vc, const uint8_t *buf, size_t size)
@@ -670,7 +670,7 @@
 {
     TAPState *s;
 
-    s = qemu_mallocz(sizeof(TAPState));
+    s = g_malloc0(sizeof(TAPState));
     if (!s)
         return -1;
     if (tap_win32_open(&s->handle, ifname) < 0) {