ADT/Triple: Switch to using .isOSDarwin() predicate.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129823 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 05ea2d2..156e017 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -51,7 +51,7 @@
 
   // If we're on Mac OS X, an 'availability' for Mac OS X attribute
   // implies visibility(default).
-  if (D->getASTContext().Target.getTriple().getOS() == llvm::Triple::Darwin) {
+  if (D->getASTContext().Target.getTriple().isOSDarwin()) {
     for (specific_attr_iterator<AvailabilityAttr> 
               A = D->specific_attr_begin<AvailabilityAttr>(),
            AEnd = D->specific_attr_end<AvailabilityAttr>();