test: rtc don't use hard coded major value

The /dev/rtc device major value may change depending on the
architecture, and kernel release. To ensure the test rtc is working
all the time, we no longer belong on hard coded major value but peek
it from /dev/rtc itself.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm/live/static/criu-rtc.c

@@ -23,19 +23,21 @@ int cr_plugin_dump_file(int fd, int id)
 	unsigned char buf[4096];
 	int img_fd, ret, len;
 	unsigned long irqp;
-	struct stat st;
+	struct stat st, st_rtc;
 
 	if (fstat(fd, &st) == -1) {
 		pr_perror("fstat");
 		return -1;
 	}
 
-#if defined(__PPC64__)
-#define RTC_DEV_MAJOR	253
-#else
-#define RTC_DEV_MAJOR	254
-#endif
-	if (major(st.st_rdev) != RTC_DEV_MAJOR || minor(st.st_rdev) != 0)
+	ret = stat("/dev/rtc", &st_rtc);
+	if (ret == -1) {
+		pr_perror("fstat");
+		return -1;
+	}
+
+	if (major(st.st_rdev) != major(st_rtc.st_rdev) ||
+	    minor(st.st_rdev) != 0)
 		return -ENOTSUP;
 
 	if (ioctl(fd, RTC_IRQP_READ, &irqp) == -1) {