Roumen:  good catch!  Indeed, nested functions aren't legal in standard C, and the test for -fno-strict-aliasing now fails on my OS X 10.6.3 machine, where it used to pass:

  checking whether gcc accepts -fno-strict-aliasing... no

config.log contains:

  configure:5400: checking whether gcc accepts -fno-strict-aliasing
  configure:5418: gcc -fno-strict-aliasing -c -g -O2  conftest.c >&5
  conftest.c: In function 'main':
  conftest.c:27: error: nested functions are disabled, use -fnested-functions to re-enable
  configure:5418: $? = 1
  configure: failed program was:
  ...

Fixed these cases above and removed the extra '#include "confdefs.h"' lines (which seem harmless, but unnecessary) in r81077 (trunk).