[AVR] Add 'none' as a valid OS

Author: Dylan McKay

include/llvm/ADT/Triple.h

@@ -144,6 +144,7 @@ class Triple {
     Win32,
     Haiku,
     Minix,
+    None,
     RTEMS,
     NaCl,       // Native Client
     CNK,        // BG/P Compute-Node Kernel

lib/Support/Triple.cpp

@@ -168,6 +168,7 @@ const char *Triple::getOSTypeName(OSType Kind) {
   case Win32: return "windows";
   case Haiku: return "haiku";
   case Minix: return "minix";
+  case None: return "none";
   case RTEMS: return "rtems";
   case NaCl: return "nacl";
   case CNK: return "cnk";
@@ -404,6 +405,7 @@ static Triple::OSType parseOS(StringRef OSName) {
     .StartsWith("windows", Triple::Win32)
     .StartsWith("haiku", Triple::Haiku)
     .StartsWith("minix", Triple::Minix)
+    .StartsWith("none", Triple::None)
     .StartsWith("rtems", Triple::RTEMS)
     .StartsWith("nacl", Triple::NaCl)
     .StartsWith("cnk", Triple::CNK)