Make use of bitfields optional for use with FFI tools.

[pieter-scholtz]

Hi , @jpfr

I am trying to get this library working with Dart's ffigen tool , and it does not support bit field members.

The structs causing that are problematic are :
UA_DataValue
UA_DiagnosticInfo
UA_DataTypeMember
UA_DataType

To my eye the solution is to make the use of bitfields in these structs optional via a Cmake option : UA_DISABLE_BITFIELDS , or something like that.

I just want to run this by you for now , If you think its a viable solution I will make a pull request. The only "problem" I can see here is that the library will be less efficient if built without bit fields , but perhaps I am missing something ?

Kind Regards.

[jpfr]

You can propose a build flag for this in a PR.
Bit-flags should be enabled by default.