Pull Lexer's CharInfo table out for general use throughout Clang.

Pull Lexer's CharInfo table out for general use throughout Clang.

Rewriting the same predicates over and over again is bad for code size and
code maintainence. Using the functions in <ctype.h> is generally unsafe
unless they are specified to be locale-independent (i.e. only isdigit and
isxdigit).

The next commit will try to clean up uses of <ctype.h> functions within Clang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174765 91177308-0d34-0410-b5e6-96231b3b80d8