Get things to compile on recent Debian vintage
Added my own continued-identifier string parser.

Perl 5.18 has the function isIDCONT, a boolean function that indicates whether
the given character is a valid continuing identifier character. Valid
characters include letters, numbers, and the underscore. Since older perls
don't provide this function, I had to write my own.
Improved shared library finding on debian
Added repeat test to libperl
Fix t/01; now compiles, but segfaults, on debian