tools/nolibc: add limits.h shim header

limits.h is a widely used standard header.  Missing it from nolibc requires
adoption effort to port applications.

Add a shim header which includes the global nolibc.h header.
It makes all nolibc symbols available.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Willy Tarreau <w@1wt.eu>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/all/20250226-parse_vdso-nolibc-v2-9-28e14e031ed8@linutronix.de