This change adds a clean target to the VC-WIN* Makefiles, then adjusts
the config generation script to call it before config file generation
as well as after. This prevents files from previous configurations from
causing make to incorrectly assume the files are up to date.

This change contains the results of running `make` in
`deps/openssl/config` (based on information in
deps/openssl/config/README.md) then reverting changes not in the
VC-WIN64-ARM directory.

This leverages a preceding change that fixes a cross-configuration file
reuse bug that only impacts VC-WIN64-ARM.

This change contains the results of running `make` in
`deps/openssl/config` (based on information in
deps/openssl/config/README.md) and not reverting anything.

This is not necessary, but it does indicate to the curious developer
that all architectures were automatically generated at the same time.