selftests: kselftest: Fix build failure with NOLIBC

BugLink: https://bugs.launchpad.net/bugs/2065912

commit 16767502aa990cca2cb7d1372b31d328c4c85b40 upstream.

As Mark explains ksft_min_kernel_version() can't be compiled with nolibc,
it doesn't implement uname().

Fixes: 6d029c25b71f ("selftests/timers/posix_timers: Reimplement check_timer_distribution()")
Reported-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240412123536.GA32444@redhat.com
Closes: https://lore.kernel.org/all/f0523b3a-ea08-4615-b0fb-5b504a2d39df@sirena.org.uk/
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>

tools/testing/selftests/kselftest.h

@@ -350,6 +350,10 @@ static inline __noreturn __printf(1, 2) int ksft_exit_skip(const char *msg, ...)
 static inline int ksft_min_kernel_version(unsigned int min_major,
 					  unsigned int min_minor)
 {
+#ifdef NOLIBC
+	ksft_print_msg("NOLIBC: Can't check kernel version: Function not implemented\n");
+	return 0;
+#else
 	unsigned int major, minor;
 	struct utsname info;
 
@@ -357,6 +361,7 @@ static inline int ksft_min_kernel_version(unsigned int min_major,
 		ksft_exit_fail_msg("Can't parse kernel version\n");
 
 	return major > min_major || (major == min_major && minor >= min_minor);
+#endif
 }
 
 #endif /* __KSELFTEST_H */