[clang-tidy] Add `const` to operator() to fix a warning.

llvm-svn: 304583

clang-tools-extra/clang-tidy/misc/LambdaFunctionNameCheck.h

@@ -25,7 +25,7 @@ namespace misc {
 class LambdaFunctionNameCheck : public ClangTidyCheck {
 public:
   struct SourceRangeLessThan {
-    bool operator()(const SourceRange &L, const SourceRange &R) {
+    bool operator()(const SourceRange &L, const SourceRange &R) const {
       if (L.getBegin() == R.getBegin()) {
         return L.getEnd() < R.getEnd();
       }