tests: add missing igt_exit() calls

Forgotten while converting to subtests, then copy&pasted.

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

tests/gem_persistent_relocs.c

@@ -381,5 +381,5 @@ int main(int argc, char **argv)
 		close(fd);
 	}
 
-	return 0;
+	igt_exit();
 }

tests/gem_reloc_vs_gpu.c

@@ -384,5 +384,5 @@ int main(int argc, char **argv)
 		close(fd);
 	}
 
-	return 0;
+	igt_exit();
 }