Backport VIRPIL Controls device IDs to SDL2

Backport of SDL3 fix (libsdl-org/SDL#15418).

VIRPIL Controls (VID 0x3344) flight sticks are
misclassified as gamepads by SDL's axis-count
heuristic because they report exactly 6 axes,
matching SDL_GAMEPAD_AXIS_COUNT. Adding them to
the appropriate device lists ensures correct
classification.

Tested on Linux (Fedora 43, kernel 6.19) with:
- R-VPC Stick MT-50CM3 (PID 0x4391)
- L-VPC Stick MT-50CM3 (PID 0x8390)
- VPC VMAX Prime Throttle (PID 0x0196)

src/joystick/SDL_joystick.c

diff --git a/src/joystick/SDL_joystick.c b/src/joystick/SDL_joystick.c
index 60b0daf..84cc062 100644
--- a/src/joystick/SDL_joystick.c
+++ b/src/joystick/SDL_joystick.c
@@ -293,6 +293,8 @@
     MAKE_VIDPID(0x046d, 0xc215), /* Logitech Extreme 3D */
     MAKE_VIDPID(0x231d, 0x0126), /* Gunfighter Mk.III ‘Space Combat Edition’ (right) */
     MAKE_VIDPID(0x231d, 0x0127), /* Gunfighter Mk.III ‘Space Combat Edition’ (left) */
+    MAKE_VIDPID(0x3344, 0x4391), /* VIRPIL Controls R-VPC Stick MT-50CM3 */
+    MAKE_VIDPID(0x3344, 0x8390), /* VIRPIL Controls L-VPC Stick MT-50CM3 */
     MAKE_VIDPID(0x362c, 0x0001), /* Yawman Arrow */
 };
 static SDL_vidpid_list flightstick_devices = {
@@ -332,6 +334,7 @@
 static Uint32 initial_throttle_devices[] = {
     MAKE_VIDPID(0x044f, 0x0404), /* HOTAS Warthog Throttle */
     MAKE_VIDPID(0x0738, 0xa221), /* Saitek Pro Flight X-56 Rhino Throttle */
+    MAKE_VIDPID(0x3344, 0x0196), /* VIRPIL Controls VPC VMAX Prime Throttle */
 };
 static SDL_vidpid_list throttle_devices = {
     SDL_HINT_JOYSTICK_THROTTLE_DEVICES, 0, 0, NULL,