[SHELL32_APITEST] Improve the existing PCH and make use of it. Convert AddCommas.c to c++ in order to have it benefit from the PCH.

modules/rostests/apitests/shell32/SHCreateFileExtractIconW.cpp

@@ -6,13 +6,12 @@
  */
 
 #include "shelltest.h"
-#include <atlbase.h>
-#include <atlcom.h>
-ULONG DbgPrint(PCH Format,...);
-#include <shellutils.h>
+
 #include <wincon.h>
 #include <wingdi.h>
 
+ULONG DbgPrint(PCH Format,...);
+#include <shellutils.h>
 
 HRESULT (STDAPICALLTYPE *pSHCreateFileExtractIconW)(LPCWSTR pszFile, DWORD dwFileAttributes, REFIID riid, void **ppv);