ggml-cpu : remove stdlib include from repack.cpp (ggml/1276)

This commit removes the inclusion of `<cstdlib>`.

The motivation for this change is that this source file does not seem to
use any functions from this header and the comment about `qsort` is a
little misleading/confusing.

ggml/src/ggml-cpu/repack.cpp

@@ -14,7 +14,6 @@
 #include <cmath>
 #include <cstring>
 #include <cassert>
-#include <cstdlib> // for qsort
 #include <cstdio>  // for GGML_ASSERT
 
 #include "repack.h"