Raymond Meyer wrote:
> #error "Compiler or options invalid for pre-UNIX 03 X/Open applications and pre-2001 POSIX applications"

This is indeed a problem, and it seemed to me that it is not yet widely 
known. Therefore I documented my thoughts about that topic here:

http://wiki.netbsd.se/index.php/Typical_pkgsrc_error_messages
http://wiki.netbsd.se/index.php/Feature_test_macros

The fix is nontrivial and must be checked individually for each instance 
of the problem.

Roland