[libcxx] Modify language.support tests so they pass or are UNSUPPORTED with c++03.

[EricWF]

Summary

A couple of misc test changes so they work with <= c++03.

[EricWF]

test/depr/depr.c.headers/stdarg_h.pass.cpp

18–22

va_copy is not defined until c++11.

test/language.support/support.start.term/quick_exit.pass.cpp

11

quick_exit was added in c++11.

test/language.support/support.types/nullptr_t.pass.cpp

57

The c++03 nullptr is only convertible to pointers and bool. This appears to be what the standard suggests. However it is not an integral type so it can't be reinterpret cast to a signed integer.

[EricWF]

Abandoning and splitting the patch into its relevant parts.

test/depr/depr.c.headers/stdarg_h.pass.cpp

 #error va_arg not defined
 #endif
 
+#if __cplusplus >= 201103L
 #ifndef va_copy
 #error va_copy not defined
 #endif
+#endif
 
 #ifndef va_end
 #error va_end not defined

test/language.support/support.runtime/cstdarg.pass.cpp

 #error va_arg not defined
 #endif
 
+#if __cplusplus >= 201103L
 #ifndef va_copy
 #error va_copy not defined
 #endif
+#endif
 
 #ifndef va_end
 #error va_end not defined

test/language.support/support.start.term/quick_exit.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // XFAIL: apple-darwin
+// UNSUPPORTED: c++98, c++03
 
 // test quick_exit and at_quick_exit
 

test/language.support/support.types/nullptr_t.pass.cpp

     assert(!(nullptr != a));
     assert(!(nullptr < a));
     assert(!(nullptr > a));
+#ifndef _LIBCPP_HAS_NO_NULLPTR
     std::ptrdiff_t i = reinterpret_cast<std::ptrdiff_t>(nullptr);
     assert(i == 0);
+#endif
 }