selftest: pidfd: Omit long and repeating outputs

An output message:

> # # waitpid WEXITSTATUS=0

will be printed for 30,000+ times in the `pidfd_test` selftest, which
does not seem ideal. This patch removes the print logic in the
`wait_for_pid` function, so each call to this function does not output
a line by default. Any existing call sites where the extra line might
be beneficial have been modified to include extra print statements
outside of the function calls.

Signed-off-by: Ziqi Zhao <[e-mail]>
Reviewed-by: Christian Brauner <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/pidfd/pidfd.h

···
 	}
 
 	ret = WEXITSTATUS(status);
-	ksft_print_msg("waitpid WEXITSTATUS=%d\n", ret);
 	return ret;
 }
 

tools/testing/selftests/pidfd/pidfd_fdinfo_test.c

···
 		r = -1;
 	}
 
+	ksft_print_msg("waitpid WEXITSTATUS=%d\n", r);
 	return r;
 }
 

tools/testing/selftests/pidfd/pidfd_test.c

···
 
 	pidfd = open(buf, O_DIRECTORY | O_CLOEXEC);
 
-	(void)wait_for_pid(pid);
+	ret = wait_for_pid(pid);
+	ksft_print_msg("waitpid WEXITSTATUS=%d\n", ret);
 
 	if (pidfd < 0)
 		ksft_exit_fail_msg(