fbo-pbo-readpixels-layers: Test glReadPixel() from FBO with layers
Tests that glReadPixel() correctly reads from FBO to GL_PIXEL_PACK_BUFFER buffer. With either specific layer and level of texture bound to FBO via glFramebufferTextureLayer(), or entire layered texture bound via glFramebufferTexture().
Texture is filled via GL_PIXEL_UNPACK_BUFFER to test both upload and download code.
Accessing each level/layer of textures that created with different amount of layers and levels (from 1 to MAX_MIPLEVEL, MAX_LAYERS_NUM). Texture targets tested: GL_TEXTURE_1D_ARRAY, GL_TEXTURE_2D_ARRAY, GL_TEXTURE_CUBE_MAP, GL_TEXTURE_CUBE_MAP_ARRAY, GL_TEXTURE_3D.
Tests: mesa/mesa#4144 (closed) Tests: mesa/mesa#4115 (closed)
Signed-off-by: Yevhenii Kharchenko yevhenii.kharchenko@globallogic.com