From: David Mosberger <davidm@napali.hpl.hp.com>

Below is a patch that tries to sanitize the dropping of unneeded system-call
stubs in generic code.  In some instances, it would be possible to move the
optional system-call stubs into a library routine which would avoid the need
for #ifdefs, but in many cases, doing so would require making several
functions global (and possibly exporting additional data-structures in
header-files).  Furthermore, it would inhibit (automatic) inlining in the
cases in the cases where the stubs are needed.  For these reasons, the patch
keeps the #ifdef-approach.

This has been tested on ia64 and there were no objections from the
arch-maintainers (and one positive response).  The patch should be safe but
arch-maintainers may want to take a second look to see if some __ARCH_WANT_foo
macros should be removed for their architecture (I'm quite sure that's the
case, but I wanted to play it safe and only preserved the status-quo in that
regard).