mesa: Fix error reporting for some cases of incomplete FBO attachments

According to the OpenGL and OpenGL ES specs (sections
"FRAMEBUFFER COMPLETENESS" and "Whole Framebuffer Completeness"),
the image for color, depth or stencil attachments must be renderable,
otherwise the attachment is considered incomplete and we should report
GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT. Currently, we detect this
situation properly but report a different error.

This fixes the following 3 piglit tests:
dEQP-GLES3.functional.fbo.completeness.renderable.texture.color0.rgb_unsigned_int_2_10_10_10_rev
dEQP-GLES3.functional.fbo.completeness.renderable.texture.color0.rgba_unsigned_int_2_10_10_10_rev
dEQP-GLES3.functional.fbo.completeness.renderable.texture.color0.rgb16f
mesa: Returns correct error values from gl(Get)SamplerParameter*() in GLES3

Per GLES specification, the family of functions glGetSamplerParameter(iv/fv)
and glSamplerParameter(i/f/iv/fv) return an INVALID_OPERATION error if
sampler is not the name of a sampler object previously returned from a call
to GenSamplers.
In desktop GL, an GL_INVALID_VALUE is returned instead.

Fixes 6 dEQP failing tests:
* dEQP-GLES3.functional.negative_api.shader.get_sampler_parameteriv
* dEQP-GLES3.functional.negative_api.shader.get_sampler_parameterfv
* dEQP-GLES3.functional.negative_api.shader.sampler_parameteri
* dEQP-GLES3.functional.negative_api.shader.sampler_parameteriv
* dEQP-GLES3.functional.negative_api.shader.sampler_parameterf
* dEQP-GLES3.functional.negative_api.shader.sampler_parameterfv