Revert "test/gem_concurrent_blt"

This reverts commit aee0dcb1ec.

Oops, accidentally commit a bit of wip changes.

lib/drmtest.c

@@ -1129,6 +1129,7 @@ static void fork_helper_exit_handler(int sig)
 bool __igt_fork_helper(struct igt_helper_process *proc)
 {
 	pid_t pid;
+	sighandler_t oldsig;
 	int id;
 
 	assert(!proc->running);
@@ -1145,6 +1146,7 @@ bool __igt_fork_helper(struct igt_helper_process *proc)
 	 * that inserting sufficient amounts of printf or other delays makes
 	 * this unnecessary.
 	 */
+	oldsig = signal(SIGQUIT, SIG_DFL);
 	switch (pid = fork()) {
 	case -1:
 		igt_assert(0);
@@ -1155,6 +1157,8 @@ bool __igt_fork_helper(struct igt_helper_process *proc)
 
 		return true;
 	default:
+		signal(SIGQUIT, oldsig);
+
 		proc->running = true;
 		proc->pid = pid;
 		proc->id = id;