Bug 1432410 - Add tests in tree to make sure we don't regress with clang-tidy on static-analisys. Tests wrote in part by :sylvestre. r=gps

MozReview-Commit-ID: IWxzKfWNIHG

tools/clang-tidy/test/readability-redundant-string-cstr.cpp

@@ -0,0 +1,7 @@
+#include "structures.h"
+
+void foo() {
+  std::string a = "Mozilla";
+  std::string tmp;
+  tmp.assign(a.c_str());
+}