[Mips][msa] Add support for half

Add support for half (a.k.a. __fp16) in builtin descriptions. 
The second argument to BUILTIN() now accepts 'h' to represent half.

Patch by Daniel Sanders

llvm-svn: 188464

clang/include/clang/Basic/Builtins.def

@@ -25,6 +25,7 @@
 //  c -> char
 //  s -> short
 //  i -> int
+//  h -> half
 //  f -> float
 //  d -> double
 //  z -> size_t

clang/lib/AST/ASTContext.cpp

@@ -7552,6 +7552,11 @@ static QualType DecodeTypeFromStr(const char *&Str, const ASTContext &Context,
            "Bad modifiers used with 'v'!");
     Type = Context.VoidTy;
     break;
+  case 'h':
+    assert(HowLong == 0 && !Signed && !Unsigned &&
+           "Bad modifiers used with 'f'!");
+    Type = Context.HalfTy;
+    break;
   case 'f':
     assert(HowLong == 0 && !Signed && !Unsigned &&
            "Bad modifiers used with 'f'!");