Resurect preprocessor definitions that got lost moving to HostInfo

When building without XCode on sytems where these constants are
not in the system header (or I presume with older versions of XCode),
these are needed to make this file compile, since unlike most other
uses of MachO specific constants, these use the system headers
rather than the LLVM-defined ones.

llvm-svn: 216332

lldb/source/Host/macosx/HostInfoMacOSX.mm

@@ -30,6 +30,16 @@
 #include <mach-o/dyld.h>
 #include <objc/objc-auto.h>
 
+// These are needed when compiling on systems
+// that do not yet have these definitions
+#include <AvailabilityMacros.h>
+#ifndef CPU_SUBTYPE_X86_64_H
+#define CPU_SUBTYPE_X86_64_H ((cpu_subtype_t)8)
+#endif
+#ifndef CPU_TYPE_ARM64
+#define CPU_TYPE_ARM64 (CPU_TYPE_ARM|CPU_ARCH_ABI64)
+#endif
+
 using namespace lldb_private;
 
 bool