SEH regression on Windows for x86 bundles based on ESR 78

A cypherpunk noted that checking for SafeSEH fails now in 32bit Windows bundles based on ESR 78.

According to them it comes from https://reviews.llvm.org/D63570#1565447. Martin Storsjö landed a patch to implement the --no-seh flag that should help with that: https://reviews.llvm.org/D84701#2177048.

I think this is not as dramatic as it sounds because as Martin writes

"Mingw mode compilers don't use SEH at all in i386 mode at the moment though"

Thus, even if we would not set the --no-seh flag SEH would not kick in for our 32bit bundles.