Add build support for < macOS 12

smc.c

@@ -57,7 +57,13 @@ kern_return_t SMCOpen(void)
     io_object_t device;
 
     CFMutableDictionaryRef matchingDictionary = IOServiceMatching("AppleSMC");
+
+    #if MAC_OS_X_VERSION_10_16
         result = IOServiceGetMatchingServices(kIOMainPortDefault, matchingDictionary, &iterator);
+    #else
+        result = IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDictionary, &iterator);
+    #endif
+    
     if (result != kIOReturnSuccess) {
         printf("Error: IOServiceGetMatchingServices() = %08x\n", result);
         return 1;