NFC: Fix ClassDecl inline bitfield count

Author: hamishknight

include/swift/AST/Decl.h

@@ -531,7 +531,7 @@ class alignas(1 << DeclAlignInBits) Decl {
     NumRequirementsInSignature : 16
   );
 
-  SWIFT_INLINE_BITFIELD(ClassDecl, NominalTypeDecl, 2+1+1+2+1+7+1+1+1+1+1+1,
+  SWIFT_INLINE_BITFIELD(ClassDecl, NominalTypeDecl, 2+1+1+2+1+1+1+1+1+1,
     /// The stage of the inheritance circularity check for this class.
     Circularity : 2,