Sorry about the (possibly off) question: would this apply also to GMP/MPFR, if not, wouldn't it make sense?
GMP and MPFR are host libraries, so it is actually an independent issue. However, it might be worth having --with-static-gmp and --with-static-mpfr to request static linking of these libraries into the compiler. I think I suggested the idea (maybe even a patch, but I can't find it in the mailing-list archives) when gmp/mpfr was still only used by Fortran. In the end, some people will think it's stretching the configury too much for a specific purpose, and some people will think it's just a good option to have. (I'm in the second group.) Let's wait and see what people think of the idea. FX