Avoid llvm-nm / llvm-objcopy special cases for mingw

[nikic]

#100178 switched a few places that previously used llvm-nm / llvm-objcopy to use nm / objcopy instead, because the LLVM tools have some kind of output redirection / piping issue with the new toolchain.

We should figure out what the root cause of this is an try to fix it somewhere.

Example:

rust/tests/run-make/native-link-modifier-bundle/Makefile

Lines 6 to 13 in c7bf469

	# We're using the llvm-nm instead of the system nm to ensure it is compatible
	# with the LLVM bitcode generated by rustc.
	# Except on Windows where piping/IO redirection under MSYS2 is wonky with llvm-nm.
	ifndef IS_WINDOWS
	NM = "$(LLVM_BIN_DIR)"/llvm-nm
	else
	NM = nm
	endif

[mati865]

FWIW this issue affects all Windows targets because these tools are used on both MSVC and GNU.

@rustbot modify labels: -O-windows-gnu +O-windows

[mati865]

I think this patch could solve this issue but I haven't tested: https://reviews.llvm.org/D142224

Also cross-linking issue at MSYS2: msys2/MINGW-packages#9044

Update: it didn't help.