Remove yet-unused 64-bit atomic hooks.

src/ports/SkAtomics_win.h

Index: src/ports/SkAtomics_win.h
diff --git a/src/ports/SkAtomics_win.h b/src/ports/SkAtomics_win.h
index 4b344dde779a1ee1f548495d7c6d1b1e346b2231..a1876d269b883be505b130e58ce27a616bc297f9 100644
--- a/src/ports/SkAtomics_win.h
+++ b/src/ports/SkAtomics_win.h
@@ -34,30 +34,17 @@ static inline int32_t sk_atomic_add(int32_t* addr, int32_t inc) {
     return _InterlockedExchangeAdd(reinterpret_cast<long*>(addr), static_cast<long>(inc));
 }
 
-static inline int64_t sk_atomic_add(int64_t* addr, int64_t inc) {
-    return InterlockedExchangeAdd64(addr, inc);
-}
-
 static inline int32_t sk_atomic_dec(int32_t* addr) {
     // InterlockedDecrement returns the new value, we want to return the old.
     return _InterlockedDecrement(reinterpret_cast<long*>(addr)) + 1;
 }
 
-static inline int64_t sk_atomic_dec(int64_t* addr) {
-    // InterlockedDecrement returns the new value, we want to return the old.
-    return InterlockedDecrement64(addr) + 1;
-}
-
 static inline void sk_membar_acquire__after_atomic_dec() { }
 
 static inline bool sk_atomic_cas(int32_t* addr, int32_t before, int32_t after) {
     return _InterlockedCompareExchange(reinterpret_cast<long*>(addr), after, before) == before;
 }
 
-static inline bool sk_atomic_cas(int64_t* addr, int64_t before, int64_t after) {
-    return _InterlockedCompareExchange64(addr, after, before) == before;
-}
-
 static inline void* sk_atomic_cas(void** addr, void* before, void* after) {
     return InterlockedCompareExchangePointer(addr, after, before);
 }