Two fixes related to pathsearchmode
Fix 1: Mapster32: Remove "pathsearchmode" backup from menuselect()
Hitting CTRL+F in Mapster32's map load menu, then exiting it with ESC would result in the next menu opening at the filesystem's root path, and not in the previously open folder.
Fix 2: Duke3D: Fix pathsearchmode when using a .def which loads a GRP
Same fix as applied for Mapster32 in c7aa59b0