Changed isPrint for U+00AD SOFT HYPHEN to return true.

Summary:
This is consistent with MacOSX implementation, and most terminals
actually display this character (checked on gnome-terminal, lxterminal, lxterm,
Terminal.app, iterm2). Actually, this is in line with the ISO Latin 1 standard
(ISO 8859-1), which defines it differently from the Unicode Standard. More
information here: http://www.cs.tut.fi/~jkorpela/shy.html

Reviewers: gribozavr, jordan_rose

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1310