(gtk2_ardour) Remove the reliance on libfst, which we no longer build

(fst's functionality has now mostly been moved into libardour)
Add some new modules, needed for building the VST scanner app with MSVC
When running an (MSVC built) VST scanner app, make sure we can utilise debuggable versions if we need to
Remove an unneeded icon when building the VST scanner app with MSVC
When building with MSVC, guard a declaration of 'strdup()' which conflicts slightly with the MSVC declaration

(maybe we should just #include <string.h> ?)
Modify 'msvc32-fixup.pl' for building the VST scanner app resources
When building with MSVC undef type VOID if we're declaring an enum called VOID
Add some newly introduced source files to our MSVC project (gtk2_ardour)
Add some newly introduced header files to our MSVC project (libs/ardour)