make Symbol::dump conditional on debug build type.

Author: schweitzpgi

flang/include/flang/Semantics/symbol.h

@@ -650,7 +650,9 @@ class Symbol {
   // for a parameterized derived type instantiation with the instance's scope.
   const DerivedTypeSpec *GetParentTypeSpec(const Scope * = nullptr) const;
 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
   LLVM_DUMP_METHOD void dump() const { llvm::errs() << *this << '\n'; }
+#endif
 
 private:
   const Scope *owner_;