switch to clang-cl when using .bat / .ps1 activation

[h-vetinari]

Not sure why our default here on windows is

clang-win-activation-feedstock/recipe/activate-clang_win-64.bat

Lines 3 to 5 in 7d3aacb

	set "CC=clang.exe"
	set "NM=llvm-nm.exe"
	set "LD=lld-link.exe"

This is inconsistent in the sense that lld-link does not recognize -L (needs /LIBPATH:), wheras clang.exe does not recognize /LIBPATH: and needs -L.

IMO it would make sense for our clang compilers on windows to default to clang-cl; alternatively we could consider having separate compilers called clang{,xx}-cl_win-64? Then it would just be a matter of doing the following in CBC:

 c_compiler:                # [win]
-- clang                    # [win]
+- clang-cl                 # [win]
 cxx_compiler:              # [win]
-- clangxx                  # [win]
+- clangxx-cl               # [win]

Thoughts @xhochy @isuruf?

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

[xhochy]

We should have separate compilers. In the cases where I use clang for Windows, I actually want clang.exe.