use macro for replace malloc api (see skynet_malloc.h)

skynet-src/skynet_malloc.h

@@ -0,0 +1,18 @@
+#ifndef skynet_malloc_h
+#define skynet_malloc_h
+
+#include <stddef.h>
+
+#define malloc skynet_malloc
+#define calloc skynet_calloc
+#define realloc skynet_realloc
+#define free skynet_free
+
+void * skynet_malloc(size_t sz);
+void * skynet_calloc(size_t nmemb,size_t size);
+void * skynet_realloc(void *ptr, size_t size);
+void skynet_free(void *ptr);
+char * skynet_strdup(const char *str);
+void * skynet_lalloc(void *ud, void *ptr, size_t osize, size_t nsize);	// use for lua
+
+#endif