tests/igt: restore dmesg-by-default

This regression has been introduced in

commit 90a25641164c8a0c8cc09a5515864b654df9d368
Author: Dylan Baker <baker.dylan.c@gmail.com>
Date:   Mon Jan 27 11:23:28 2014 -0800

    Use the new dmesg class

The original logic to always capture dmesg for igt tests has been
added in

commit da3819f07ca2b74b386ee96b8af1e141c36ec8ce
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Mon Nov 11 22:04:32 2013 +0100

    igt: Enable dmesg checking by default

Cc: Dylan Baker <baker.dylan.c@gmail.com>
Reviewed-by: Dylan Baker <baker.dylan.c@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
gl-3.2-depth-tex-sampling: Check return value of piglit_check_gl_error.

Fixes "Unchecked return value" defects reported by Coverity.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Brian Paul <brianp@vmware.com>
Add a GLSL ES 3.00 compiler test for chained qualifiers.

Mesa had a bug where using an "auxiliary storage qualifier" (to use the
420pack terminology) such as "centroid" would lose any precision
qualifiers.

This simple test trips that bug.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reported-by: Kevin Rogovin <kevin.rogovin@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
line-flat-clip-color: Initialize variable.

Fixes "Uninitialized scalar variable" defect reported by Coverity.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Brian Paul <brianp@vmware.com>