Always use FVIRTKEY for the accelerators under MSW.

Always use FVIRTKEY for the accelerators under MSW.

Not using FVIRTKEY results in problems in non-US keyboard layouts and, in
fact, we were already always using it because wxCharCodeWXToMSW() returned
true in its output IsVirtual argument most of the time.

Just do it always now and also remove IsVirtual parameter with badly (if at
all...) defined meaning from wxCharCodeWXToMSW() as it's not used anywhere any
longer.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62913 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775