[tidy] Move private ast matchers into anonymous namespaces to avoid ODR conflicts.

No functionality change intended.

llvm-svn: 325467
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp
index 923555b..3e800cd 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp
@@ -17,9 +17,11 @@
 namespace tidy {
 namespace cppcoreguidelines {
 
+namespace {
 AST_MATCHER(GotoStmt, isForwardJumping) {
   return Node.getLocStart() < Node.getLabel()->getLocStart();
 }
+} // namespace
 
 void AvoidGotoCheck::registerMatchers(MatchFinder *Finder) {
   if (!getLangOpts().CPlusPlus)