tests: roll out igt_simple_init/igt_simple_main

Also use igt_skip a bit more to simplify some of the tests.

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

tests/core_getversion.c

@@ -32,7 +32,7 @@
 /**
  * Checks DRM_IOCTL_GET_VERSION and libdrm's drmGetVersion() interface to it.
  */
-int main(int argc, char **argv)
+igt_simple_main
 {
 	int fd;
 	drmVersionPtr v;
@@ -45,5 +45,4 @@ int main(int argc, char **argv)
 	igt_assert(v->version_major >= 1);
 	drmFree(v);
 	close(fd);
-	return 0;
 }