[client] egl: replace monolithic EGLTexture with modular version

The way things were handled in EGLTexture is not only very hard to
follow, but broken. This change set breaks up EGLTexture into a modular
design making it easier to implement the various versions.

Note that DMABUF is currently broken and needs to be re-implemented.

client/renderers/EGL/texture_util.h

@@ -0,0 +1,54 @@
+/**
+ * Looking Glass
+ * Copyright (C) 2017-2021 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but 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., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#pragma once
+
+#include "texture.h"
+
+typedef struct EGL_TexFormat
+{
+  size_t       bpp;
+  GLenum       format;
+  GLenum       intFormat;
+  GLenum       dataType;
+  unsigned int fourcc;
+  size_t       bufferSize;
+
+  size_t       width, height;
+  size_t       stride, pitch;
+}
+EGL_TexFormat;
+
+typedef struct EGL_TexBuffer
+{
+  size_t size;
+  GLuint pbo;
+  void * map;
+  GLsync sync;
+  bool   updated;
+}
+EGL_TexBuffer;
+
+bool eglTexUtilGetFormat(const EGL_TexSetup * setup, EGL_TexFormat * fmt);
+bool eglTexUtilGenBuffers(const EGL_TexFormat * fmt, EGL_TexBuffer * buffers,
+    int count);
+void eglTexUtilFreeBuffers(EGL_TexBuffer * buffers, int count);
+bool eglTexUtilMapBuffer(EGL_TexBuffer * buffer);
+void eglTexUtilUnmapBuffer(EGL_TexBuffer * buffer);