Fix persistent GL_INVALID_OPERATION spam and resolution-change bugs on Android

- opengl_end_frame() bound framebuffer 0 on Android, which has no valid
  target there (real presentation goes through the OpenXR swapchain's own
  FBOs) - gl4es reported this every frame. Skip it there.
- render_hack_cameras() re-entered opengl_start_frame()/opengl_end_frame()
  for camera-monitor renders that never touch the GL screen; excluded them
  to match use_opengl()'s existing behavior. Also drains a stray error left
  by xrPollEvent().
- ChangeScreenSize() never called opengl_resize() on Android, freezing the
  3D render target at launch size after an in-game resolution change; and
  xr_get_game_resolution() used the swapchain's fixed size instead of the
  current screen resolution, misplacing the laser-pointer cursor after such
  a change.
- Removes all temporary bisection diagnostics added while tracking down the
  GL_INVALID_OPERATION source.

android/app/src/main/cpp/xr_session.c

@@ -319,6 +319,14 @@ void xr_poll_events(void) {
             }
         }
     }
+
+    // xrPollEvent() leaves gl4es reporting a stray GL_INVALID_OPERATION on
+    // every call while the session is running - drain it (looped, since
+    // more than one can accumulate across xrPollEvent()'s possibly-multiple
+    // iterations above) so it doesn't surface as a false positive at the
+    // next unrelated glGetError() check in this app's own rendering code.
+    while (glGetError() != GL_NO_ERROR) {
+    }
 }
 
 bool xr_is_session_running(void) { return g_session_running; }
@@ -434,6 +442,7 @@ void xr_frame_end(void) {
     endInfo.environmentBlendMode = XR_ENVIRONMENT_BLEND_MODE_OPAQUE;
     endInfo.layerCount = layerCount;
     endInfo.layers = layerCount > 0 ? layers : NULL;
+
     xr_check(xrEndFrame(g_session, &endInfo), "xrEndFrame");
 }
 
@@ -471,6 +480,21 @@ void xr_get_game_quad_extent(float *distance_m, float *half_width_m, float *half
 }
 
 void xr_get_game_resolution(int *width, int *height) {
-    *width = g_game_swapchain.width;
-    *height = g_game_swapchain.height;
+    // Not g_game_swapchain.width/height: that's the fixed physical size of
+    // the swapchain image the game is composited into (see xr_init()) -
+    // android_draw_surface_as_quad() (OpenGL.cc, engine-patches/11) always
+    // stretch-blits drawSurface to fill that image regardless of
+    // drawSurface's own pixel size, so the swapchain's size has no relation
+    // to the coordinate space MouseX/MouseY actually live in. gScreenWide/
+    // gScreenHigh (InitMac.h) is drawSurface's current size - the
+    // resolution the in-game options menu can change at runtime
+    // (ShockBitmap.c's ChangeScreenSize()) independently of the swapchain,
+    // which is created once at launch and never resized. Using the fixed
+    // swapchain size here after such a change mapped the laser pointer's
+    // quad-space hit into the wrong coordinate space entirely, moving
+    // MouseX/MouseY out of the engine's actual screen bounds - which is
+    // what made the cursor disappear and become unclickable.
+    extern int32_t gScreenWide, gScreenHigh;
+    *width = gScreenWide;
+    *height = gScreenHigh;
 }