Undefined behavior in LogConfiguration::configure_stdout.

The new XCode9 cannot be used for jdk because it cause a build failure in LogConfiguration::configure_stdout.

The output is:
============================
open/src/hotspot/share/logging/logConfiguration.cpp:303:16: error: passing an object that undergoes default argument promotion to 'va_start' has undefined behavior [-Werror,-Wvarargs]
  va_start(ap, exact_match);
               ^
open/src/hotspot/share/logging/logConfiguration.cpp:299:66: note: parameter of type 'bool' is declared here
void LogConfiguration::configure_stdout(LogLevelType level, bool exact_match, ...) {
                                                                 ^
1 error generated.
============================

http://en.cppreference.com/w/cpp/language/variadic_arguments#Default_conversions

"bool, char, short, and unscoped enumerations are converted to int or wider integer types as in integer promotion "

"The behavior of the va_start macro is undefined if the last parameter before the ellipsis has reference type, or has type that is not compatible with the type that results from default argument promotions."