defines in system headers

[Shane Ambler]

I ran into a problem with /usr/include/xlocale/_ctype.h in 9.1

Line 56 is -
#if __GNUC__ && !__GNUC_STDC_INLINE__


but within a tinderbox on a 9.0 system (yes I know that setup isn't 
actually supported) using gcc as the compiler __GNUC_STDC_INLINE__ isn't 
defined and generates a "!" has no right operand error.

Isn't the correct way to test that

#if defined(__GNUC__) && !defined(__GNUC_STDC_INLINE__)