Support external toolchain on Windows for aot compiler (#3911)

allowing custom ARC toolchain on Windows

core/shared/utils/bh_common.h

@@ -66,6 +66,16 @@ bh_strdup(const char *s);
 char *
 wa_strdup(const char *s);
 
+#if WASM_ENABLE_WAMR_COMPILER != 0 || WASM_ENABLE_JIT != 0
+/* Executes a system command in bash/cmd.exe */
+int
+bh_system(const char *cmd);
+
+/* Tests whether can create a temporary file with the given name */
+bool
+bh_mkstemp(char *filename, size_t name_len);
+#endif
+
 #ifdef __cplusplus
 }
 #endif