Namespace anonymous enum

[eignnx]

https://github.com/eignnx/dynarray/blob/master/dynarray.h#L14-L19

This anonymous enum uses up some semi-common identifiers like LENGTH which may appear in application code that uses this library. The enum members should be renamed to something specific to the dynarray library. Or maybe there's a way to keep the names private by using #define LENGTH and #undef LENGTH.

Also the name LENGTH is not very descriptive. Probably something like LENGTH_FIELD_OFFSET would make more sense.