Sema: Don't type check enum element default args in non-primary files

Move the checking from validateDecl() to typeCheckDecl() since there's no
need to do it unless we're going to be emitting the enum declaration.

Author: slavapestov

lib/Sema/TypeCheckDecl.cpp

@@ -2941,6 +2941,9 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
     TC.validateDecl(EED);
     TC.checkDeclAttributes(EED);
 
+    if (auto *PL = EED->getParameterList())
+      TC.checkDefaultArguments(PL, EED);
+
     checkAccessControl(TC, EED);
   }
 
@@ -4098,7 +4101,6 @@ void TypeChecker::validateDecl(ValueDecl *D) {
                                                     EED->getParentEnum(),
                                                     ED->getGenericSignature()),
                              TypeResolverContext::EnumElementDecl);
-      checkDefaultArguments(PL, EED);
     }
 
     // If we have a raw value, make sure there's a raw type as well.