8327444: simplify RESTARTABLE macro usage in JDK codebase

Reviewed-by: gli, clanger, alanb, dholmes, bpb

src/java.base/linux/native/libnio/fs/LinuxNativeDispatcher.c

@@ -50,12 +50,6 @@ typedef ssize_t copy_file_range_func(int, loff_t*, int, loff_t*, size_t,
                                      unsigned int);
 static copy_file_range_func* my_copy_file_range_func = NULL;
 
-#define RESTARTABLE(_cmd, _result) do { \
-  do { \
-    _result = _cmd; \
-  } while((_result == -1) && (errno == EINTR)); \
-} while(0)
-
 static void throwUnixException(JNIEnv* env, int errnum) {
     jobject x = JNU_NewObjectByName(env, "sun/nio/fs/UnixException",
         "(I)V", errnum);