This is a simple macro for executing a block of code at the beginning of
intel-gpu-tools, before any tests have been ran. Useful for
initialization of global resources used in IGT libraries.

Signed-off-by: Lyude <lyude@redhat.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

Changes since v1:
 - Add the line number into the name of the constructor function so that
   multiple constructors may be used per-file.