ctype: use less short names in public header

ctype: use less short names in public header

We're seeing a build failure in GNU sim code which is using _P locally
but the ctype.h define clashes with it.  Rename these to use the same
symbols that glibc does.  They're a bit more verbose, but seems likely
that we'll have fewer conflicts if glibc isn't seeing them.

However, these shortnames are still used internally by ctype modules
to produce pretty concise source code, so move the short names to the
internal ctype_.h where short name conflicts shouldn't show up.