[PATCH 0/4] POSIX_* Wundef fixes

[Siddhesh Poyarekar]

This patch set fixes Wundef warnings for all POSIX_* macros and also
proposes a way to organize all of the sysconf variables so that
they're generated from one place (posix/conf.list) and are hence
typo-proof.  All patches have been verified on x86_64 to ensure that
they don't result in any significant changes in generated code.

[PATCH 1/4] Remove Wundef warnings for specification macros

- This is the initial patch that adds the conf.list file and macros
  and fixes one set of warnings.

[PATCH 2/4] Add _POSIX namespace SYSCONF macros to conf.list

- This is the second patch that adds the POSIX namespace sysconf
  macros to the list and fixes the remaining warnings.

[PATCH 3/4] Use PTHREAD_DESTRUCTOR_ITERATIONS

- This patch replaces the POSIX_THREAD_DESTRUCTOR_ITERATIONS with a
  view to unify getconf and sysconf usage.

[PATCH 4/4] Use conf.list to generate spec array

- This patch removes the hand-written specs variable and replaces it
  with an auto-generated array.  The vars array can be similarly
  replaced after adding all of its constituent variables to conf.list.
  I'll do that once these patches are in.

Siddhesh