perfect: Refactor deinitializeIfNeeded for Performance and Safety

This commit adjusts the deinitializeIfNeeded method in MalomSolutionAccess
to enhance performance and ensure safety. The check for a null pointer
(pp == nullptr) is moved to the beginning of the method. This change
prevents unnecessary cleanup calls and potential double deletion issues,
improving both the performance and robustness of the code. By returning
early when pp is null, we avoid redundant cleanup operations and align
with the intended idempotent nature of the function.

Reference: ggevay/malom#3 (comment)
Change-Id: I6b77af22f99ad500217f1a70145144b33c1f20fb

src/perfect/perfect_api.cpp

@@ -167,12 +167,12 @@ void MalomSolutionAccess::initializeIfNeeded()
 
 void MalomSolutionAccess::deinitializeIfNeeded()
 {
-    Rules::cleanup();
-
     if (pp == nullptr) {
         return;
     }
 
+    Rules::cleanup();
+
     delete pp;
 
     pp = nullptr;