bug.h: make BUILD_BUG_ON generate compile-time error

Negative sized arrays wont create a compile-time error in some cases
starting with gcc 4.4 (e.g., inlined functions), but gcc 4.3 introduced
the error function attribute that will.

This patch modifies BUILD_BUG_ON to behave like BUILD_BUG already does,
using the error function attribute so that you don't have to build the
entire kernel to discover that you have a problem, and then enjoy trying
to track it down from a link-time error.

Also, we are only including asm/bug.h and then expecting that
linux/compiler.h will eventually be included to define __linktime_error
(used in BUILD_BUG_ON).  This patch includes it directly for clarity and
to avoid the possibility of changes in <arch>/*/include/asm/bug.h being
changed or not including linux/compiler.h for some reason.

Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joe Perches <joe@perches.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>