Add BOOST_NO_CXX11_EXCECPTION.

Replaces: https://github.com/boostorg/config/pull/285
Fixes https://github.com/boostorg/config/issues/284
See also: https://github.com/boostorg/exception/issues/10

include/boost/config/stdlib/vacpp.hpp

@@ -51,6 +51,7 @@
 #  define BOOST_NO_CXX11_HDR_ATOMIC
 #  define BOOST_NO_CXX11_STD_ALIGN
 #  define BOOST_NO_CXX11_ADDRESSOF
+#  define BOOST_NO_CXX11_HDR_EXCEPTION
 
 #if defined(__has_include)
 #if !__has_include(<shared_mutex>)