Windows / macOS: simplify code

1. simplify resource management by using C++ RAII like GCC attribute extension `cleanup`
2. simplify HEKY reading

Actually `__attribute__((__cleanup__(cleanupFn)))` is supported on all major C compiler ( gcc, clang and icc ) except MSVC I only used it on Windows and macOS for now. Let's see if the project author like it.

src/detection/battery/battery_apple.c

@@ -7,7 +7,7 @@
 
 static double detectBatteryTemp()
 {
-    FFlist temps;
+    FF_LIST_AUTO_DESTROY temps;
     ffListInit(&temps, sizeof(FFTempValue));
 
     ffDetectCoreTemps(FF_TEMP_BATTERY, &temps);
@@ -25,7 +25,6 @@ static double detectBatteryTemp()
         ffStrbufDestroy(&tempValue->deviceClass);
     }
     result /= temps.length;
-    ffListDestroy(&temps);
     return result;
 }