Warn on and drop dllimport attrs from variable definitions

AsmPrinter::EmitLinkage() does not handle dllimport linkage.  The LLVM
verifier should also be fixed to reject this.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182320 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index 627bc3d..be4bd0e 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -2725,9 +2725,8 @@
   bool isDef = false;
   if (!D->canBeWeakImported(isDef)) {
     if (isDef)
-      S.Diag(Attr.getLoc(),
-             diag::warn_attribute_weak_import_invalid_on_definition)
-        << "weak_import" << 2 /*variable and function*/;
+      S.Diag(Attr.getLoc(), diag::warn_attribute_invalid_on_definition)
+        << "weak_import";
     else if (isa<ObjCPropertyDecl>(D) || isa<ObjCMethodDecl>(D) ||
              (S.Context.getTargetInfo().getTriple().isOSDarwin() &&
               (isa<ObjCInterfaceDecl>(D) || isa<EnumDecl>(D)))) {