[lldb/Platform] Re-add ifdef's to guard macOS-only code.

I moved the code from the system initializer to PlatformMacOSX. The
defines are still necessary because MacOSX is initialized on other
platforms where the other platforms are not available.

Author: JDevlieghere

lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.cpp

@@ -7,13 +7,15 @@
 //===----------------------------------------------------------------------===//
 
 #include "PlatformMacOSX.h"
+#if defined(__APPLE__)
 #include "PlatformAppleTVSimulator.h"
 #include "PlatformAppleWatchSimulator.h"
 #include "PlatformDarwinKernel.h"
 #include "PlatformRemoteAppleBridge.h"
 #include "PlatformRemoteAppleTV.h"
 #include "PlatformRemoteAppleWatch.h"
 #include "PlatformiOSSimulator.h"
+#endif
 #include "lldb/Breakpoint/BreakpointLocation.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/ModuleList.h"
@@ -40,13 +42,15 @@ static uint32_t g_initialize_count = 0;
 
 void PlatformMacOSX::Initialize() {
   PlatformDarwin::Initialize();
+#if defined(__APPLE__)
   PlatformiOSSimulator::Initialize();
   PlatformDarwinKernel::Initialize();
   PlatformAppleTVSimulator::Initialize();
   PlatformAppleWatchSimulator::Initialize();
   PlatformRemoteAppleTV::Initialize();
   PlatformRemoteAppleWatch::Initialize();
   PlatformRemoteAppleBridge::Initialize();
+#endif
 
   if (g_initialize_count++ == 0) {
 #if defined(__APPLE__)
@@ -67,13 +71,15 @@ void PlatformMacOSX::Terminate() {
     }
   }
 
+#if defined(__APPLE__)
   PlatformRemoteAppleBridge::Terminate();
   PlatformRemoteAppleWatch::Terminate();
   PlatformRemoteAppleTV::Terminate();
   PlatformAppleWatchSimulator::Terminate();
   PlatformAppleTVSimulator::Terminate();
   PlatformDarwinKernel::Terminate();
   PlatformiOSSimulator::Terminate();
+#endif
   PlatformDarwin::Terminate();
 }