ggml : build backends as libraries (#10256)

* ggml : build backends as libraries

---------

Signed-off-by: Xiaodong Ye <xiaodong.ye@mthreads.com>
Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
Co-authored-by: R0CKSTAR <xiaodong.ye@mthreads.com>

ggml/src/ggml-amx/common.h

@@ -1,7 +1,8 @@
 #pragma once
 
 #include "ggml.h"
-#include "ggml-cpu-impl.h" // <immintrin.h>
+// hack until AMX is moved into the CPU backend
+#include "../ggml-cpu/ggml-cpu-impl.h" // <immintrin.h>
 
 #include <algorithm>
 #include <memory>