[PATCH] gfortran -- Map REAL128 to REAL kind type with widest precision

[FX]

Hi Steve,

I see Mikael has okayed the patch, but I did not have any time to comment prior. I wanted to note that:

 - the choice was deliberate, as the standard allows us to choose which real kind REAL128 corresponds to when there are several matching choices. The idea behind the current choice was to avoid forcing the use of slower soft-float arithmetic when a hardware type existed. I don’t have a strong opinion myself on the issue.

 - This is a breakage of the ABI, so we want to write it in the release notes, and in the doc about ISO_FORTRAN_ENV.

 - Is this appropriate for stage 4?

FX