I was having a go at the library portion of PR 30512, which
requires a bit of m4 hacking, and I found that "./configure
--enable-maintainer-mode" in libgfortran, followed by adding "M4=m4"
to the top of the Makefile and running "make generated/*" failed,
due to the new dependency tracking, with lots of error messages like
Makefile:1404: .deps/transpose_c4.Plo: No such file or directory
Makefile:1405: .deps/transpose_c8.Plo: No such file or directory
Makefile:1406: .deps/transpose_generic.Plo: No such file or directory
Any idea on how to get this to work?