Remove unused constexpr

Summary:
@public

Removes unused constexpr variables from YGStyle. Not polluting the global namespace is a good thing.

Reviewed By: SidharthGuglani

Differential Revision: D13816817

fbshipit-source-id: e4c27a8f2de466ccb759bbe52cdaea6fe451b961

Author: davidaurelio

ReactCommon/yoga/yoga/YGStyle.h

@@ -20,10 +20,6 @@
 #define BITFIELD_ENUM_SIZED(num)
 #endif
 
-constexpr YGValue kYGValueUndefined = {0, YGUnitUndefined};
-
-constexpr YGValue kYGValueAuto = {0, YGUnitAuto};
-
 struct YGStyle {
 private:
   using CompactValue = facebook::yoga::detail::CompactValue;