[tuples] Merged trunk->branch @132948

[Diego Novillo]

It had been a while, so this merge was fairly long.  It exposed a bug
in complex lowering (we were not splitting the basic block properly
when expanding complex divisions) and the ppc back end still hadn't
been updated for the new walk_gimple_stmt interface.

I also changed all the gimple_locus() and related functions to use
'location' instead of 'locus'.  Tom Tromey's location_t patch is now
in the branch so we don't have to deal with the ugly #ifdefs.  The
function gimple_locus_empty_p was mostly used with a ! in front, so I
changed it to gimple_has_location to make predicates easier to read.

Tested on x86, x86_64 and ppc64.


Diego.