- (dtucker) [configure.ac] Make PIE a configure-time option which defaults
   to on platforms where it's known to be reliably detected and off elsewhere.
   Works around platforms such as FreeBSD 9.1 where it does not interop with
   -ftrapv (it seems to work but fails when trying to link ssh).  ok djm@
 - (dtucker) [aclocal.m4] Differentiate between compile-time and link-time
   tests in the configure output.  ok djm.