ggml : build backends as libraries (llama/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-threading.cpp

@@ -0,0 +1,12 @@
+#include "ggml-threading.h"
+#include <mutex>
+
+std::mutex ggml_critical_section_mutex;
+
+void ggml_critical_section_start() {
+    ggml_critical_section_mutex.lock();
+}
+
+void ggml_critical_section_end(void) {
+    ggml_critical_section_mutex.unlock();
+}