Stripping `-lmingwex` from the Fortran standard linker flags can lead to
a situation where the first `-lmsvcrt` can appear before the first
`-lmingwex` for a library that consists of Fortran and C++ sources.
That means that the linker picks some functions from the Windows CRT that
should instead be picked from `libmingwex.a`.
It took quite some time to figure out an odd behavior when calling
`std::asin` with a complex double precision value with a real part larger
than 1 in such a library.
See also: https://octave.discourse.group/t/6026/75
Also don't strip `-lmoldname` from these flags because there is no reason
to do that as far as I can tell.
This essentially reverts the upstream changes from:
https://lists.gnu.org/r/autoconf-patches/2021-09/msg00000.html
