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/os-posix.c b/os-posix.c
index bb803c1..75d68b5 100644
--- a/os-posix.c
+++ b/os-posix.c
@@ -135,12 +135,12 @@
 
     max_len = strlen(dir) +
         MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
-    res = qemu_mallocz(max_len);
+    res = g_malloc0(max_len);
     snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
     if (access(res, R_OK)) {
         snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
         if (access(res, R_OK)) {
-            qemu_free(res);
+            g_free(res);
             res = NULL;
         }
     }