handy.h: Allow bootstrapping to non-ASCII platform

handy.h: Allow bootstrapping to non-ASCII platform

This adds a bunch of macros and moves things around to support
conditional compilation when Configure is called with
-DBOOTSTRAP_CHARSET.  Doing so causes the usual macros that are
table-driven to not be used, since the table may not be valid when
bringing Perl up for the first time on a non-ASCII platform.

This allows it to compile using the platform's native C library ctype
functions, which should work enough to compile miniperl, and allow the
table to be changed to be valid.  Then Configure can be re-run to not
bootstrap, and normal compilation can proceed