t/io/through.t: Generalize for non-ASCII platforms

This uses hard-coded values for EBCDIC because of the shell issues
t/op/magic.t: Generalize for non-ASCII platforms
t/uni/method.t: Generalize for non-ASCII platforms

I couldn't figure out a way to not use the hard-coded values
t/uni/parser.t: Generalize for non-ASCII platforms
lib/utf8.t: Generalize for non-ASCII platforms
XXX finish up lib/dumpvar.pl: Generalize for EBCDIC

Has octal constants
lib/DBM_Filter/t/encode.t: Generalize for non-ASCII platforms
ext/XS-APItest/t/svpv_magic.t: Generalize for non-ASCII platforms
ext/XS-APItest/t/svpeek.t: Generalize for non-ASCII platforms
XXX skip cpan tests
XXX: Experiment with malformed utf8
dist/ExtUtils-Install/t/InstallWithMM.t: Skip if EBCDIC

Because is uses JSON
t/porting/regen.t: Add file to check
re/reg_email.t: Generalize for non-ASCII platforms

This replaces all the hard-coded hex character values.  It uses the new
(?[ ]) notation.  I checked that the compiled regex matches the exact
same code points as before these changes.
t/op/warn.t: Generalize for non-ASCII platforms
dist/Safe/t/safeutf8.t: Generalize to non-ASCII platform
ext/B/t/b.t: Generalize for non-ASCII platforms
XXX finish up t/re/regexp.t: Generalize for non-ASCII platforms

This adds code to the processing of the tests in t/re/re_tests to
automatically convert from unicode to native character sets

Add comment about circular tests
XXX better commit message
unicode_constants.h: regened for ebcdic
t/io/crlf.t: Generalize for non-ASCII platforms