lib/os: With CBPRINTF_NANO, picolibc long-long printf isn't required

CBPRINTF_FULL_INTEGRAL doesn't happen to explicitly conflict with
CBPRINTF_NANO, but when CBPRINTF_NANO is enabled, there's no long long I/O
support provided.

Allow picolibc long-long I/O support to also be elided when CBPRINTF_NANO
is enabled to save similar amounts of space.

Signed-off-by: Keith Packard <keithp@keithp.com>