[clang-tidy] Add support for different char-types for the readability-redundant-string-cstr checker.
Summary:
The current checker is able to recognize std::string but does not recognize other string variants.
This patch is adding the support for any string defined with basic_string without considering the
the underlying char type.
The most common variant is: 'std::wstring' based on 'wchar_t'.
There are also other string variants added to the standard: u16string, u32string, etc...
Reviewers: alexfh
Subscribers: mamai, dblaikie, cfe-commits
Differential Revision: http://reviews.llvm.org/D18412
llvm-svn: 264325