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/qobject/qerror.c b/qobject/qerror.c
index 0f47be0..40d0cbb 100644
--- a/qobject/qerror.c
+++ b/qobject/qerror.c
@@ -221,7 +221,7 @@
 {
     QError *qerr;
 
-    qerr = qemu_mallocz(sizeof(*qerr));
+    qerr = g_malloc0(sizeof(*qerr));
     QOBJECT_INIT(qerr, &qerror_type);
 
     return qerr;
@@ -459,5 +459,5 @@
     qerr = qobject_to_qerror(obj);
 
     QDECREF(qerr->error);
-    qemu_free(qerr);
+    g_free(qerr);
 }