lib/igt.cocci: Add s/assert/igt_assert/

People use it way too often, and it upsets the test library. The only
valid places to use this is of igt infrastructure self-tests where you
need to check something _without_ all the other abi use checks
igt_fail and friends do. For those tests just #define an internal
assert to hide it.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

lib/igt.cocci

@@ -84,3 +84,10 @@ expression pipe;
 + for_each_pipe (display, pipe) {
 ...
 }
+
+// Tests really shouldn't use plain assert!
+@@
+expression E;
+@@
+- assert(E);
++ igt_assert(E);