Try fixing build on VC

c:\projects\harfbuzz\src\hb-set-private.hh(151): error C2327: 'hb_set_t::page_t::v': is not a type name, static, or enumerator [C:\projects\harfbuzz\build\harfbuzz.vcxproj]
diff --git a/src/hb-set-private.hh b/src/hb-set-private.hh
index be0a90d..689766c 100644
--- a/src/hb-set-private.hh
+++ b/src/hb-set-private.hh
@@ -148,7 +148,7 @@
 
     static const unsigned int ELT_BITS = sizeof (elt_t) * 8;
     static const unsigned int ELT_MASK = ELT_BITS - 1;
-    static const unsigned int BITS = sizeof (v) * 8;
+    static const unsigned int BITS = sizeof (vector_t) * 8;
     static const unsigned int MASK = BITS - 1;
     static_assert (PAGE_BITS == BITS, "");