[clang-tidy] Fix FP with readability-redundant-string-init for default arguments
Summary:
Clang-tidy is reporting a warning of redundant string initialisation
on a string parameter initialized with empty string.
See bug: 27087
The reported example is:
#include <string> void fn(std::string a = "");
Reviewers: alexfh
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D18829