Update to today's snapshot, apply patches for r600 GPU clock
    
    - glsl: Only allow `invariant` on shader in/out between stages. (Chris Forbes)
    - mesa: Fix error code generation in glReadPixels() (Anuj Phogat)
    - mesa: Add an error condition in glGetFramebufferAttachmentParameteriv() (Anuj Phogat)
    - mesa: Add error condition for integer formats in glGetTexImage() (Anuj Phogat)
    - mesa: Add helper function _mesa_is_format_integer() (Anuj Phogat)
    - i965: Fix component mask and varying_to_slot mapping for gl_ViewportIndex (Anuj Phogat)
    - i965: Fix component mask and varying_to_slot mapping for gl_Layer (Anuj Phogat)
    - i965: Put an assertion to check valid varying_to_slot[varying] (Anuj Phogat)
    - mesa: fix GetStringi error message with correct function name (Benjamin Bellec)
    - mesa: Fix error condition for multisample proxy texture targets (Anuj Phogat)
    - swrast: Add glBlitFramebuffer to commands affected by conditional rendering (Anuj Phogat)
    - st/xa: Cache render target surface (Thomas Hellstrom)
    - mesa: fix check for dummy renderbuffer in _mesa_FramebufferRenderbufferEXT() (Samuel Iglesias Gonsalvez)
    - mesa: Fix glGetVertexAttribi(GL_VERTEX_ATTRIB_ARRAY_SIZE) (Anuj Phogat)
    - r600g: Disable LLVM by default at runtime for graphics (Michel Dänzer)
    
    Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>