Summary provider for char.

This patch enables type summary for 'char' type. Given:
    char c = 'h';
Before this patch, c evaluates as:
    (char) $0 = 'h'
After this patch, we get:
    (char) $0 = 104 'h'
This change allows the formatting of character types in MI to be removed
and replaced with that in lldb, and can be useful when evaluating
non-printable characters.

Patch from evgeny.leviant@gmail.com
Reviewed by: granata.enrico
Subscribers: lldb-commits
Differential Revision: http://reviews.llvm.org/D13657

llvm-svn: 251080