Commit 8c8b7419b6 defined Shift-F5 and Shift-F6 to adjust the VR
handling. However, Shift-F5 and Shift-F6 already had a meaning: drop
primary weapon / drop secondary weapon. The ordering of the logic
causes the new VR handling to suppress the old drop handling, thus
preventing players from dropping weapons. Disable the VR meaning for
these keys so that drop-weapon works again, since F1 documents those
keys as drop-weapon.
Fixes: 8c8b7419b6 ("Improved conditionals for stereo vs non-stereo modes.")