[RecursiveASTVisitor] Do not inline TraverseStmt (NFC) (#107601)

As things are now, this reduces size of clang bootstrapped with ThinLTO
by 0.3% and reduces thin link time by 0.3%. More importantly, it avoids
a large regression once #107114
is merged. Without this change, there would be a 0.4% regression in code
size and 4% (!) regression in thin link time. There is no impact on
run-time performance.

Author: nikic

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -652,9 +652,11 @@ bool RecursiveASTVisitor<Derived>::PostVisitStmt(Stmt *S) {
 
 #undef DISPATCH_STMT
 
+// Inlining this method can lead to large code size and compile-time increases
+// without any benefit to runtime performance.
 template <typename Derived>
-bool RecursiveASTVisitor<Derived>::TraverseStmt(Stmt *S,
-                                                DataRecursionQueue *Queue) {
+LLVM_ATTRIBUTE_NOINLINE bool
+RecursiveASTVisitor<Derived>::TraverseStmt(Stmt *S, DataRecursionQueue *Queue) {
   if (!S)
     return true;