Properly support fake multisample
If the host driver supports only fake multisample (i.e. number of samples == 1) then the following dEQP tests fail:
dEQP-GLES31.functional.shaders.builtin_functions.texture_size.samples_1_texture_2d
dEQP-GLES31.functional.shaders.builtin_functions.texture_size.samples_1_texture_2d_array
dEQP-GLES31.functional.shaders.builtin_functions.texture_size.samples_1_texture_int_2d
dEQP-GLES31.functional.shaders.builtin_functions.texture_size.samples_1_texture_int_2d_array
dEQP-GLES31.functional.shaders.builtin_functions.texture_size.samples_1_texture_uint_2d
dEQP-GLES31.functional.shaders.builtin_functions.texture_size.samples_1_texture_uint_2d_array