Add controller input and a laser-pointer-driven menu quad

- xr_input.c/h: an OpenXR action set (aim pose, trigger/select click, a
  menu-toggle button) plus ray/quad hit-testing, and a visible
  laser-pointer line drawn from the controller toward the hit point.
- xr_menu.c/h + MenuOverlay.java: a second composition-layer quad,
  toggled by a controller button, showing an off-screen, never-attached
  Android View tree (one "Keyboard" button so far) driven by synthetic
  touch events computed from the laser ray's hit UV.
- Migrate gl4es from a prebuilt binary baked into the Docker build-image
  to a vendored source snapshot (android/gl4es-src/) compiled from
  source at APK build time via CMake add_subdirectory(), patched through
  a new android/gl4es-patches/ (mirrors the existing engine-patches/
  pattern). This was needed to track down and fix a bug hit while
  building the menu: gl4es's fixed-pipeline emulation (fpe.c) was
  unconditionally substituting its own shader onto the menu's draw call
  (fpe_ReleventState() always sets alphafunc to a nonzero sentinel, so
  its fpe_IsEmpty() check could never see the state as empty), making
  the menu quad show the game's own rendering instead of its own
  content. Fixed by routing the menu's blit through a real
  glBlitFramebuffer() call instead of a shader-based draw, which gl4es's
  fpe.c has nothing to intercept - documented in README.md's new
  "Debugging notes" section.
- Renumber android/engine-patches/ to close the gap left by removing an
  unrelated diagnostic-only patch, and strip investigation-journal
  comments and dead diagnostic code (temporary tracing, env-var probes)
  left over from finding the bug above.
- Restructure README.md into numbered sections, document every
  engine/gl4es patch, add Android Studio dev/testing-cycle instructions,
  and generalize Quest-specific wording to any OpenXR headset. Update
  NOTICE.txt to match (gl4es is now vendored/patched source, not a
  prebuilt binary; add the OpenXR-SDK loader).

android/gl4es-src/bc_cat.h

@@ -0,0 +1,84 @@
+/**********************************************************************
+ *
+ * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
+ * Copyright(c) 2008 Imagination Technologies Ltd. All rights reserved.
+ * 
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope it will be useful but, except 
+ * as otherwise stated in writing, without any warranty; without even the 
+ * implied warranty of merchantability or fitness for a particular purpose. 
+ * See the GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * The full GNU General Public License is included in this distribution in
+ * the file called "COPYING".
+ *
+ * Contact Information:
+ * Imagination Technologies Ltd. <gpl-support@imgtec.com>
+ * Home Park Estate, Kings Langley, Herts, WD4 8LZ, UK 
+ *
+ ******************************************************************************/
+
+#ifndef __BC_CAT_H__
+#define __BC_CAT_H__
+
+#include <linux/ioctl.h>
+
+#define BC_FOURCC(a,b,c,d) \
+    ((unsigned long) ((a) | (b)<<8 | (c)<<16 | (d)<<24))
+
+#define BC_PIX_FMT_NV12     BC_FOURCC('N', 'V', '1', '2') /*YUV 4:2:0*/
+#define BC_PIX_FMT_UYVY     BC_FOURCC('U', 'Y', 'V', 'Y') /*YUV 4:2:2*/
+#define BC_PIX_FMT_YUYV     BC_FOURCC('Y', 'U', 'Y', 'V') /*YUV 4:2:2*/
+#define BC_PIX_FMT_RGB565   BC_FOURCC('R', 'G', 'B', 'P') /*RGB 5:6:5*/
+
+enum BC_memory {
+    BC_MEMORY_MMAP          = 1,
+    BC_MEMORY_USERPTR       = 2,
+};
+
+typedef struct BCIO_package_TAG {
+    int input;
+    int output;
+}BCIO_package;
+
+/* 
+ * the following types are tested for fourcc in struct bc_buf_params_t
+ *   NV12
+ *   UYVY
+ *   RGB565 - not tested yet
+ *   YUYV
+ */
+typedef struct bc_buf_params {
+    int count;              /*number of buffers, [in/out]*/
+    int width;              /*buffer width in pixel, multiple of 8 or 32*/
+    int height;             /*buffer height in pixel*/
+    unsigned int fourcc;    /*buffer pixel format*/
+    enum BC_memory type;
+} bc_buf_params_t;
+
+typedef struct bc_buf_ptr {
+    unsigned int index;
+    int size;
+    unsigned long pa;
+} bc_buf_ptr_t;
+
+#define BCIO_GID                    'g'
+#define BC_IOWR(INDEX)            _IOWR(BCIO_GID, INDEX, BCIO_package)
+
+#define BCIOGET_BUFFERCOUNT       BC_IOWR(0)  /*obsolete, since BCIOREQ_BUFFERS
+                                                return the number of buffers*/
+#define BCIOGET_BUFFERPHYADDR     BC_IOWR(1)  /*get physical address by index*/
+#define BCIOGET_BUFFERIDX         BC_IOWR(2)  /*get index by physical address*/
+
+#define BCIOREQ_BUFFERS           BC_IOWR(3)
+#define BCIOSET_BUFFERPHYADDR     BC_IOWR(4)
+
+#endif 
+