[Piglit] Tests for ARB_shader_image_load_store (resend).

[Francisco Jerez]

This is my third and last rebase and resend of the
ARB_shader_image_load_store tests I sent to this mailing list last
October.  If there have been no objections by the 3rd February at noon
(UTC) I will push the rest of the series without review.

[PATCH 01/23] util/shader: Define "nothrow" variant of piglit_compile_shader_text().
[PATCHv2 02/23] arb_shader_image_load_store: Add common image metadata.
[PATCHv2 03/23] arb_shader_image_load_store: Import grid execution helpers.
[PATCH 04/23] arb_shader_image_load_store: Add misc. image manipulation code and hook up to the build system.
[PATCHv2 05/23] arb_shader_image_load_store: Import atomicity image built-in tests.
[PATCHv2 06/23] arb_shader_image_load_store: Import image format bitcasting test.
[PATCH 07/23] arb_shader_image_load_store: Import memory coherency test.
[PATCH 08/23] arb_shader_image_load_store: Import dead fragments test.
[PATCH 09/23] arb_shader_image_load_store: Import early_fragment_tests test.
[PATCHv2 10/23] arb_shader_image_load_store: Import host memory barrier tests.
[PATCHv2 11/23] arb_shader_image_load_store: Import image array indexing test.
[PATCH 12/23] arb_shader_image_load_store: Import invalid and undefined image access tests.
[PATCH 13/23] arb_shader_image_load_store: Import tests for layered and unlayered binding.
[PATCH 14/23] arb_shader_image_load_store: Import test for mipmap level binding.
[PATCHv2 15/23] arb_shader_image_load_store: Import tests for the maximum of supported images.
[PATCH 16/23] arb_shader_image_load_store: Import test for the maximum texture size.
[PATCH 17/23] arb_shader_image_load_store: Import minimum maximum test.
[PATCH 18/23] arb_shader_image_load_store: Import memory access qualifier test.
[PATCH 19/23] arb_shader_image_load_store: Import image aliasing test.
[PATCH 20/23] arb_shader_image_load_store: Import built-in semantics tests.
[PATCH 21/23] arb_shader_image_load_store: Import shader memory barrier tests.
[PATCH 22/23] arb_shader_image_load_store: Import image unit and uniform state tracking tests.
[PATCH 23/23] arb_shader_image_load_store: Import test for atomics with unused result.