build-wolfssl: Update VS properties for wolfSSL v3.9.0

- Do not use wolfSSL's sample user-setting files.

wolfSSL starting in v3.9.0 has added their own sample user settings that
are applied by default, but we don't use them because we have our own
settings.

- Do not use wolfSSL's Visual Studio Unicode character setting.

wolfSSL Visual Studio projects use the Unicode character set however our
settings and options imitate mingw build which does not use the Unicode
character set. This does not appear to have any effect at the moment but
better safe than sorry.


These changes are backwards compatible with earlier versions.