Visual Studio projects: Add include path for FriBidi

The Fribidi headers tend to be under $(PREFIX)\include\fribidi\, so we
want to try to look for these headers in there as well.
2 jobs for gtk-3-24 in 8 minutes and 15 seconds (queued for 11 seconds)
Status Job ID Name Coverage
  Build
passed #222871
build

00:08:15

manual #222872
win32 allowed to fail manual
msys2-mingw32