opengles emulator: code cleanup removing dead code

This change removes the 'blitFromPbuffer' path in the renderer
which uses binding pbuffer to texture. This path does not work
on all platforms and is not relavent any more. It simplifies
a lot the FBConfig filtering code.

Also, added a check to fail the renderer initialization if
the translator plugin does not support EGL_KHR_gl_texture_2d_image
and GL_OES_EGL_IMAGE (by both GLES implementations [1 and 2])
since our implementation requires it.

Change-Id: Ifd4c66943a8da56308cfb7e38914c962b4f5befe

tools/emulator/opengl/host/libs/libOpenglRender/FrameBuffer.h

@@ -35,7 +35,6 @@ struct FrameBufferCaps
     bool hasGL2;
     bool has_eglimage_texture_2d;
     bool has_eglimage_renderbuffer;
-    bool has_BindToTexture;
     EGLint eglMajor;
     EGLint eglMinor;
 };