fix Widestring vs. Ansi mixup

(cherry picked from commit 4dcb4a41022085aa82f25f7e0a2ce9e92510f4ae)

src/corelib/io/qprocess_win.cpp

@@ -294,7 +294,7 @@ QProcessEnvironment QProcessEnvironment::systemEnvironment()
             }
             entry += entryLen + 1;
         }
-        FreeEnvironmentStrings(envStrings);
+        FreeEnvironmentStringsW(envStrings);
     }
     return env;
 }