Propolice stack protector merged in -current

[Miod Vallat <miod@online.fr>]

Hello folks,

  as hinted by Theo a few hours ago, the propolice stack protection gcc
mods have been merged in the tree.

  We have choosen to enable propolice by default to ensure that it will
get widely tested, in the hope that this will prove a worthy addition
for our next releases. Expect some breakage in ports, though, that will
get fixed as time permits.

  If you are updating your system by source, please be sure to compile
and install an updated ld.so (libexec/ld.so on ELF platforms,
gnu/usr.bin/ld/rtld on a.out platforms) before you start a make build.
The make build phase will also build and install a new libc first, that
provides some code needed by propolice-enabled binaries.

Miod