[PATCH] GNU libc __stack_chk_fail detection

[Alfred M. Szmidt]

   I have just been pointed that Hurd is actually *-*-gnu (my primary
   goal was to match GNU/kFreeBSD). Please find an updated patch
   below.

GNU is actually "*-*-gnu*"; i386-pc-gnu0.3 is for example a valid
tripplet.