external/conscrypt: switch NativeCrypto itself to use NativeConstants.
external/conscrypt: switch NativeCrypto itself to use NativeConstants.

Now that other users of the constants in NativeCrypto have been switched
over, those constants can be removed.

Bug: 20521989
Change-Id: I276a1c8daeb3501b6924ff68cf9f1e9f6fbd63a9

google/conscrypt,google/conscrypt,google/conscrypt,google/conscrypt,google/conscrypt,google/conscrypt