arb_texture_multisample: add new test for errors

Tests that glFramebufferTextureLayer produces the correct error for
layer < 0 when used with GL_TEXTURE_2D_MULTISAMPLE_ARRAY. This was
overlooked in the initial mesa implementation of
ARB_texture_multisample, and crashed deep in the driver instead.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
rude hack: use smaller formats in texturing tests.

RGBA32I, RGBA32UI, and RGBA32F are huge and
unsupported for multisample textures on at least Gen6 i965.

This shouldn't be committed as-is, but it allowed for testing of
multisample samplers with the generic textureSize() test.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>