[RenderEngine] Organize RenderEngine directory.

This patch:
1. adds proper namespace renderengine to all RenderEngine code,
   and namespace gl to all GLES related code
2. creates gl/ directory for GLES backend code
3. Reorder include header files, remove unused header files.

BUG: 112585051
Test: Build, flash, run display validation
Change-Id: I81f0b8831213607cde08562958f7c38ddaf4c9e6
diff --git a/services/surfaceflinger/BufferLayer.cpp b/services/surfaceflinger/BufferLayer.cpp
index 1bb7a85..3e2fb2e 100644
--- a/services/surfaceflinger/BufferLayer.cpp
+++ b/services/surfaceflinger/BufferLayer.cpp
@@ -58,7 +58,7 @@
         mRefreshPending(false) {
     ALOGV("Creating Layer %s", name.string());
 
-    mTexture.init(Texture::TEXTURE_EXTERNAL, mTextureName);
+    mTexture.init(renderengine::Texture::TEXTURE_EXTERNAL, mTextureName);
 
     mPremultipliedAlpha = !(flags & ISurfaceComposerClient::eNonPremultiplied);
 
@@ -608,7 +608,7 @@
 
     // TODO: we probably want to generate the texture coords with the mesh
     // here we assume that we only have 4 vertices
-    Mesh::VertexArray<vec2> texCoords(getBE().mMesh.getTexCoordArray<vec2>());
+    renderengine::Mesh::VertexArray<vec2> texCoords(getBE().mMesh.getTexCoordArray<vec2>());
     texCoords[0] = vec2(left, 1.0f - top);
     texCoords[1] = vec2(left, 1.0f - bottom);
     texCoords[2] = vec2(right, 1.0f - bottom);