[Bug target/10901] non-local goto's don't work on darwin

[iains at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10901

--- Comment #25 from Iain Sandoe <iains at gcc dot gnu.org> 2012-01-18 18:29:12 UTC ---
Created attachment 26370
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26370
initial fix

this shares some changes with the fix to PR51784 (and that is somewhere to read
about the issues that prevent an easier fix).

AFAICT, the bugs are still present in the Apple OS tree - at least they are
with 4.2.1/5577 - which postdates the comments here.

Anyway, this is a starting point - I expect that there is scope to tidy it up.

As things stand we need to differentiate the load-picbase from the
reload-picbase on PPC because more of the work is done in the md.  On x86 it's
hidden away in i386.c - which made it easier to fix there.