Tiny cleanup, as suggested by David Blaikie.

llvm-svn: 196959
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 834c189..1a4ced7 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -3375,8 +3375,8 @@
     if (!Record->isUnion())
       return false;
 
-    FieldDecl *Active = ActiveUnionMember.lookup(Record->getCanonicalDecl());
-    if (Active)
+    if (FieldDecl *Active =
+            ActiveUnionMember.lookup(Record->getCanonicalDecl()))
       return Active != Field->getCanonicalDecl();
 
     // In an implicit copy or move constructor, ignore any in-class initializer.