RUBY_ASSERT_NOASSUME

If __builtin_assume() is enables and RUBY_DEBUG=0, RUBY_ASSERT(expr)
will be compiled to __builtin_assume(expr) and compiler can assume
expr is true and apply aggressive optimizations. However we observed
doubtful behavior because of compiler optimizations, we introduce
new macro RUBY_ASSERT_NOASSUME to disable __builtin_assume().
With this macro, we can try without __builtin_assume().

include/ruby/assert.h

@@ -101,7 +101,7 @@ RBIMPL_SYMBOL_EXPORT_END()
 # define RBIMPL_ASSERT_OR_ASSUME(_) RUBY_ASSERT(_)
 #elif defined(RBIMPL_HAVE___ASSUME)
 # define RBIMPL_ASSERT_OR_ASSUME(_) RBIMPL_ASSUME(_)
-#elif RBIMPL_HAS_BUILTIN(__builtin_assume) && RBIMPL_COMPILER_SINCE(Clang, 7, 0, 0)
+#elif !RUBY_ASSERT_NOASSUME && RBIMPL_HAS_BUILTIN(__builtin_assume) && RBIMPL_COMPILER_SINCE(Clang, 7, 0, 0)
 # define RBIMPL_ASSERT_OR_ASSUME(_) RBIMPL_ASSUME(_)
 #else
 # define RBIMPL_ASSERT_OR_ASSUME(_) /* void */