Deprecating GCC extensions...

[Neil Booth]

Whilst we're on the topic of deprecating extensions, is there any support
for deprecating multi-line strings for GCC 3.0?

Of course, it will still be supported and not warned about when caused
by system header macros (glibc's stdlib/longlong.h uses it), but it
would be nice to be able to remove this extension a couple of years
down the line.  We already reject it in directives other than #define.
I really hate it with a vengeance, particularly as it's 100% redundant.

Neil.