mesa: Considers GL_DEPTH_STENCIL_ATTACHMENT a valid argument for FBO invalidation...

mesa: Considers GL_DEPTH_STENCIL_ATTACHMENT a valid argument for FBO invalidation under GLES3

In OpenGL and OpenGL-ES 3+, GL_DEPTH_STENCIL_ATTACHMENT is a valid attachment point for the family of functions
that invalidate a framebuffer object (e.g, glInvalidateFramebuffer, glInvalidateSubFramebuffer, etc).
Currently, a GL_INVALID_ENUM error is emitted for this attachment point.

Fixes 21 dEQP test failures under 'dEQP-GLES3.functional.fbo.invalidate.*'.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>