PLT refs dependent upon gcc version...

[David Miller]

I've got an issue on sparc wherein the localplt testcase will
give different results depending upon the GCC version.

It has to do with references to the soft-float routines for long
double math.

Up-to and including gcc-4.6 it always generates a reference to
_Q_fle but in gcc-4.7 it no longer does.  It's due to a change
in the way float comparisons are emitted on sparc.

It seems that we need to have a way to say "a reference to this
symbols would be OK, but a lack of such a reference is fine too"