BUILD_BUG_ON_INVALID() is a macro that, like the kernel counterpart,
expands to an expression that generates no code. Useful for making
sure an expression is valid code while producing no side effects.

igt_assume() is an assert-like macro that is used to give hints to
static analysis of code. If static analysis is not used (as detected
by STATIC_ANALYSIS_BUILD), igt_assume() expands to a
BUILD_BUG_ON_INVALID, otherwise expands to an assert().

v2: Make sure the expression in igt_assume is still parsed without
    static analysis. (Chris)

v3: Also introduce BUILD_BUG_ON_INVALID as standalone

Signed-off-by: Petri Latvala <petri.latvala@intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>