[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_framebuffer.c

@@ -0,0 +1,59 @@
+/**
+ * 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
+ */
+
+#include "texture.h"
+
+#include <assert.h>
+
+#include "texture_buffer.h"
+#include "common/debug.h"
+
+static bool eglTexFB_update(EGL_Texture * texture_, const EGL_TexUpdate * update)
+{
+  TextureBuffer * this = UPCAST(TextureBuffer, texture_);
+  assert(update->type == EGL_TEXTYPE_FRAMEBUFFER);
+
+  LG_LOCK(this->copyLock);
+
+  framebuffer_read(
+    update->frame,
+    this->buf[this->bufIndex].map,
+    this->format.stride,
+    this->format.height,
+    this->format.width,
+    this->format.bpp,
+    this->format.stride
+  );
+
+  this->buf[this->bufIndex].updated = true;
+  LG_UNLOCK(this->copyLock);
+
+  return true;
+}
+
+EGL_TextureOps EGL_TextureFrameBuffer =
+{
+  .init        = eglTexBuffer_stream_init,
+  .free        = eglTexBuffer_free,
+  .setup       = eglTexBuffer_stream_setup,
+  .update      = eglTexFB_update,
+  .process     = eglTexBuffer_stream_process,
+  .bind        = eglTexBuffer_stream_bind
+};