Recognize Intel compiler as MSVC one under Windows in the build options.

The two compilers are binary compatible and by pretending that Intel compiler
is the same as MSVC, we allow using ICC to build applications using DLLs built
with MSVC.

Closes #9437.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76425 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775