Test some corner cases of loop analysis.

As of Mesa d7fa9eb, two of these tests are known to fail:

- vs-call-in-nested-loop.shader_test
- vs-inner-loop-modifies-outer-loop-var.shader_test

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Test that a layered fbo can have attachments with different layer counts.
Revert "framework: Add support for a test timeout"

This reverts commit ab2eb660925e3680e868c5f469a4ef32e6dd9a59.

Conflicts:
	framework/status.py
WIP: loop analysis tests
WIP: test clear color with mismatched layer count
Swappy swap