When running any kind of static analysis on IGT, one tends to drown in
warnings about using uninitialized variables in subtests, because
static analysis is unable to figure out that igt_fixture blocks are
always entered if a subtest block is entered. Aid the discovery of
correct execution flow by making static analysis always enter all
igt_fixture blocks and all subtest blocks.

Automatic discovery of static analyzers is done for Clang, Coverity
and Klocwork, using macros found by quick googling. For explicit
control on possible other analyzers, defining STATIC_ANALYSIS_BUILD=1
manually will activate this hack.

v2:
 - Hack not needed for igt_subtest()
 - Make sure igt_fixture is entered once instead of an infinite loop

v3:
 - Rebase properly...

Signed-off-by: Petri Latvala <petri.latvala@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>