bug#45303: #45303 [feature/native-comp] building error on Windows

[Andy Moreton]

On Sat 19 Dec 2020, Andrea Corallo via "Bug reports for GNU Emacs, the Swiss 
army knife of text editors" wrote:

> Right so (unless I'm forgetting something) just the zlib linker error
> should be remaining, correct?
>
> I'll have a look later in the weekend or Monday.

AS well as the zlib issue, there are two other problems that I found
when trying to build using MSYS2 Mingw64 64bit:

a) Linker error for "gcc_jit_type_get_const".
   It looks like this does not have a runtime import in comp.c, so is
   just a matter of fixing up another DLL import.

b) Linker error for "strsignal"
   This seems to be a configure problem. On master the configure test
   for strsignal fails to link, and the gnulib replacement get used.
   On the native branch the configure test links successfully, so the
   gnulib replacement does not happen. The only difference in the
   conftest command line appears to be adding libgccjit, so somehow
   that library is providing a strsignal symbol.
   Adding "ac_cv_func_strsignal=no" in nt/mingw-cfg.site appears to
   suppress this problem, but I don't know if that is the right fix.

HTH

   AndyM