Finish the ncpcall.asm/ncpcall.h to ncp.asm/ncp.h rename.
Update the Open Watcom build, object names, include directives, header guard,
README references and file-level dependency comments to use the shorter ncp
naming. The split remains the same: ncp.asm/ncp.h provide the low-level INT 21h
and Client32 requester entry points, ncpcall.c contains requester transport
helpers, and ncpapi.c contains the ncpXX_YY_* protocol API wrappers.
No behavior change.
