tests/gem_suspend: test debugfs/sysfs reads while s/r

Just a very quick hack cobbled together with /bin/sh and exec. We
can't use system since that does stupid things with singals ... Still
we need to whack the child process pretty hard to get rid of it.

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

lib/drmtest.h

@@ -243,6 +243,7 @@ void igt_waitchildren(void);
 
 struct igt_helper_process {
 	bool running;
+	bool use_SIGKILL;
 	pid_t pid;
 	int id;
 };