fbo-pbo-readpixels-small: add check of depth and stencil data
Updated test to also validate depth and stencil data, that was read from PBO with glReadPixels().
Reading GL_DEPTH_COMPONENT and GL_STENCIL_INDEX from following types: GL_DEPTH_COMPONENT16, GL_DEPTH_COMPONENT24, GL_DEPTH_COMPONENT32F, GL_DEPTH24_STENCIL8, GL_DEPTH32F_STENCIL8, each combination as separate subtest.
Tests: mesa/mesa#3775 (closed) Signed-off-by: Yevhenii Kharchenko yevhenii.kharchenko@globallogic.com