MDEV-26467 fixup for clang-9 and earlier

Before clang-10, asm goto was not supported, so we must use fetch_or().

storage/innobase/include/fil0fil.h

@@ -1539,7 +1539,10 @@ inline void fil_space_t::reacquire()
 inline bool fil_space_t::set_stopping_check()
 {
   mysql_mutex_assert_owner(&fil_system.mutex);
-#if defined __GNUC__ && (defined __i386__ || defined __x86_64__)
+#if defined __clang_major__ && __clang_major__ < 10
+  /* Only clang-10 introduced support for asm goto */
+  return n_pending.fetch_or(STOPPING, std::memory_order_relaxed) & STOPPING;
+#elif defined __GNUC__ && (defined __i386__ || defined __x86_64__)
   static_assert(STOPPING == 1U << 31, "compatibility");
   __asm__ goto("lock btsl $31, %0\t\njnc %l1" : : "m" (n_pending)
                : "cc", "memory" : not_stopped);

storage/innobase/sync/srw_lock.cc

@@ -308,7 +308,10 @@ Hence, we will manually translate fetch_or() using GCC-style inline
 assembler code or a Microsoft intrinsic function.
 
 */
-#if defined __GNUC__ && (defined __i386__ || defined __x86_64__)
+
+#if defined __clang_major__ && __clang_major__ < 10
+/* Only clang-10 introduced support for asm goto */
+#elif defined __GNUC__ && (defined __i386__ || defined __x86_64__)
 # define IF_FETCH_OR_GOTO(mem, bit, label)				\
   __asm__ goto("lock btsl $" #bit ", %0\n\t"				\
                "jc %l1" : : "m" (mem) : "cc", "memory" : label);