libc and libnx: When the libraries are built into two libraries, a user space...

libc and libnx:  When the libraries are built into two libraries, a user space library and a OS space library (as in the PROTECTED and KERNEL build).  Then the user space library must not use the OS internal interfaces; similarly, the OS must avoid using the userspace interfaces so that it does not muck the errno value or create spurious cancellation points.