Allow definition of dllimport static fields in partial specializations (PR19956)

This expands the logic from r210141 to cover partial specializations too.

llvm-svn: 210484
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index ec0c27b..09fcf1c 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9111,9 +9111,11 @@
         VD->isThisDeclarationADefinition()) {
       // We allow definitions of dllimport class template static data members
       // with a warning.
+      CXXRecordDecl *Context =
+        cast<CXXRecordDecl>(VD->getFirstDecl()->getDeclContext());
       bool IsClassTemplateMember =
-          cast<CXXRecordDecl>(VD->getFirstDecl()->getDeclContext())
-              ->getDescribedClassTemplate();
+          isa<ClassTemplatePartialSpecializationDecl>(Context) ||
+          Context->getDescribedClassTemplate();
 
       Diag(VD->getLocation(),
            IsClassTemplateMember