selftests/x86/syscall_nt: Clear weird flags after each test

Clear the weird flags before logging to improve strace output --
logging results while, say, TF is set does no one any favors.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/907bfa5a42d4475b8245e18b67a04b13ca51ffdb.1593191971.git.luto@kernel.org

tools/testing/selftests/x86/syscall_nt.c

@@ -59,6 +59,7 @@ static void do_it(unsigned long extraflags)
 	set_eflags(get_eflags() | extraflags);
 	syscall(SYS_getpid);
 	flags = get_eflags();
+	set_eflags(X86_EFLAGS_IF | X86_EFLAGS_FIXED);
 	if ((flags & extraflags) == extraflags) {
 		printf("[OK]\tThe syscall worked and flags are still set\n");
 	} else {