For some reason, we used "vc_x64_lib" as the output directory for the
libraries, but "vc_mswu_x64" as the output directory for the samples.
Place the arch suffix, i.e. "_x64" part, always after the compiler
prefix (possibly including version), for consistency with both the
library output directories and with MSBuild project files, as
build/msw/wx_setup.props uses $(wxCompilerPrefix)$(wxArchSuffix)_...
as wxIntRootDir value.
We need to explicitly link with the system libraries required in this
case, as static wxwebview library doesn't pull them in (it's also better
to link with them explicitly even when using shared libraries, but in
this case linking at least still worked due to transitive dependencies).
Check that all our public headers compile with this macro defined and
that using a char string without specifying its expected encoding
results in the expected compilation failure in this case.
