Minor rename

src/hb-atomic-private.hh

diff --git a/src/hb-atomic-private.hh b/src/hb-atomic-private.hh
index e2249e9..8179571 100644
--- a/src/hb-atomic-private.hh
+++ b/src/hb-atomic-private.hh
@@ -148,12 +148,12 @@
 
 struct hb_atomic_int_t
 {
-  hb_atomic_int_impl_t ref;
+  hb_atomic_int_impl_t v;
 
-  inline void set_unsafe (int v) { ref = v; }
-  inline int get_unsafe (void) const { return ref; }
-  inline int inc (void) { return hb_atomic_int_impl_add (const_cast<hb_atomic_int_impl_t &> (ref),  1); }
-  inline int dec (void) { return hb_atomic_int_impl_add (const_cast<hb_atomic_int_impl_t &> (ref), -1); }
+  inline void set_unsafe (int v_) { v = v_; }
+  inline int get_unsafe (void) const { return v; }
+  inline int inc (void) { return hb_atomic_int_impl_add (const_cast<hb_atomic_int_impl_t &> (v),  1); }
+  inline int dec (void) { return hb_atomic_int_impl_add (const_cast<hb_atomic_int_impl_t &> (v), -1); }
 };