[AST] Fix linker errors with the parser-only build

Author: akyrtzi

lib/AST/Decl.cpp

@@ -119,6 +119,10 @@ const clang::Module *ClangNode::getClangModule() const {
 }
 
 void ClangNode::dump() const {
+#if SWIFT_BUILD_ONLY_SYNTAXPARSERLIB
+  return; // not needed for the parser library.
+#endif
+
   if (auto D = getAsDecl())
     D->dump();
   else if (auto M = getAsMacro())

lib/AST/ExtInfo.cpp

@@ -92,6 +92,10 @@ Optional<UnexpectedClangTypeError> UnexpectedClangTypeError::checkClangType(
 }
 
 void UnexpectedClangTypeError::dump() {
+#if SWIFT_BUILD_ONLY_SYNTAXPARSERLIB
+  return; // not needed for the parser library.
+#endif
+
   auto &e = llvm::errs();
   using Kind = UnexpectedClangTypeError::Kind;
   switch (errorKind) {