Optimize single-character constant literal tests to use 'ord' instead of 'substr'.
Optimize single-character constant literal tests to use 'ord' instead of 'substr'.

cygx/nqp,cygx/nqp,perl6/nqp-rx,perl6/nqp-rx,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp