gfortran on MacOS X + PR17917

[THOMAS Paul Richard 169137]

Bill,

Well done on the OS X build - also the builds of R and octave are
interesting.  Perhaps you can post the good news on the gfortran wiki?

You are right to remind us that the patch for PR17917 is uncommitted.  There
is a peculiar problem with it that I hope to resolve before re-submitting;
in resolving the equivalences, the compiler is producing extra, redundant
unions for each and every module equivalence.  This has pushed me into
figuring out modules and a number of related PRs.  I hope to be submitting a
collection of patches soon.  You will also note that I have held fire on the
patch PR16940.  I am hot on the track of the real source of the bug and hope
to sidestep the posted fix.

Paul T