ggml : refactor online repacking (#10446)

* rename ggml-cpu-aarch64.c to .cpp

* reformat extra cpu backend.

- clean Q4_0_N_M and IQ4_0_N_M
  - remove from "file" tensor type
  - allow only with dynamic repack

- extract cpu extra bufts and convert to C++
  - hbm
  - "aarch64"

- more generic use of extra buffer
  - generalise extra_supports_op
  - new API for "cpu-accel":
     - amx
     - aarch64

* clang-format

* Clean Q4_0_N_M ref

Enable restrict on C++

* add op GGML_OP_MUL_MAT_ID for Q4_0_N_M with runtime repack

* added/corrected control on tensor size for Q4 repacking.

* Update ggml/src/ggml-cpu/ggml-cpu-aarch64.cpp

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

* Update ggml/src/ggml-cpu/ggml-cpu-aarch64.cpp

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

* add debug logs on repacks.

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

ggml/src/ggml-cpu/amx/amx.h

@@ -1,20 +1,8 @@
 #include "ggml-backend.h"
 #include "ggml-cpu-impl.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+// GGML internal header
 
 #if defined(__AMX_INT8__) && defined(__AVX512VNNI__)
-
 ggml_backend_buffer_type_t ggml_backend_amx_buffer_type(void);
-bool ggml_backend_amx_buft_is_amx(ggml_backend_buffer_type_t buft);
-bool ggml_backend_amx_device_supports_op(const struct ggml_tensor * op);
-void ggml_backend_amx_mul_mat(const struct ggml_compute_params * params, struct ggml_tensor * dst);
-size_t ggml_backend_amx_desired_wsize(const struct ggml_tensor * dst);
-
-#endif
-
-#ifdef __cplusplus
-}
 #endif