Make HvENAME** macros smaller and more efficient

Make HvENAME** macros smaller and more efficient

Brian's comments:
if xhv_name_count == 1, HvENAME_HEK_NN returns null.
So there's no need to use that macro twice. Just check for -1

The real need to make these smaller is the fact that some precompilers
(e.g. HP-UX 10.20) cannot cope with the size these have grown to.  The
precompiler has since got an option (-Hnnn) to increase the macrospace
but that option never made it to these old compilers.

Signed-off-by: H.Merijn Brand <h.m.brand@xs4all.nl>