handy.h: Remove unused macro

handy.h: Remove unused macro

This macro expands to a function or macro call that does not exist, so
this macro itself can't be being used by anyone.  It also doesn't fit
the paradigm of the other macros above it, being defined in terms of
uni instead of uvchr; nor does it really gain anything, since \s is a
posix space under locale.  The \f also appears to be a typo, based on
the commit message, it should have been \v.