[REGEDIT] Use _CrtSetDbgFlag to check memory leak

We can borrow the power of CRT debug. These changes are effective for debug version only:
- Insert #include <crtdbg.h> at main.c.
- Call _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF) at the prologue of wWinMain.

This is a follow-up of #5151 (9abd9b6) and 0998665.

base/applications/regedit/main.c

@@ -20,6 +20,10 @@
 
 #include "regedit.h"
 
+#ifdef _DEBUG
+#include <crtdbg.h>
+#endif
+
 BOOL ProcessCmdLine(WCHAR *cmdline);
 
 const WCHAR *reg_class_namesW[] = {L"HKEY_LOCAL_MACHINE", L"HKEY_USERS",
@@ -205,6 +209,11 @@ int WINAPI wWinMain(HINSTANCE hInstance,
 
     UNREFERENCED_PARAMETER(hPrevInstance);
 
+#ifdef _DEBUG
+    /* Report any memory leaks on exit */
+    _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);
+#endif
+
     /* Initialize global strings */
     LoadStringW(hInstance, IDS_APP_TITLE, szTitle, ARRAY_SIZE(szTitle));
     LoadStringW(hInstance, IDC_REGEDIT_FRAME, szFrameClass, ARRAY_SIZE(szFrameClass));