Replace worthless comments with actual preprocessor errors when including
the wrong versions of the compiler.h files.

[akpm@linux-foundation.org: make it work]
Signed-off-by: NRobert P. J. Day <rpjday@mindspring.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>