[llvm] Add MorphOS to Triple

[js]

Summary

This adds MorphOS to the Triple. It adds the enum as well as parsing.

llvm/include/llvm/ADT/Triple.h

     WASI,       // Experimental WebAssembly OS
     Emscripten,
     ShaderModel, // DirectX ShaderModel
-    LastOSType = ShaderModel
+    MorphOS,
+    LastOSType = MorphOS
   };
   enum EnvironmentType {
     UnknownEnvironment,

llvm/lib/Support/Triple.cpp

   case MacOSX: return "macosx";
   case Mesa3D: return "mesa3d";
   case Minix: return "minix";
+  case MorphOS: return "morphos";
   case NVCL: return "nvcl";
   case NaCl: return "nacl";
   case NetBSD: return "netbsd";

     .StartsWith("wasi", Triple::WASI)
     .StartsWith("emscripten", Triple::Emscripten)
     .StartsWith("shadermodel", Triple::ShaderModel)
+    .StartsWith("morphos", Triple::MorphOS)
     .Default(Triple::UnknownOS);
 }
 

llvm/unittests/ADT/TripleTest.cpp

   EXPECT_EQ(Triple::Amplification, T.getEnvironment());
   EXPECT_FALSE(T.supportsCOMDAT());
 
+  T = Triple("powerpc-unknown-morphos");
+  EXPECT_EQ(Triple::ppc, T.getArch());
+  EXPECT_EQ(Triple::UnknownVendor, T.getVendor());
+  EXPECT_EQ(Triple::MorphOS, T.getOS());
+  EXPECT_EQ(Triple::UnknownEnvironment, T.getEnvironment());
+
   T = Triple("huh");
   EXPECT_EQ(Triple::UnknownArch, T.getArch());
 }