Build without Diracxx fails

[s6pepaul]

I am trying to build hdgeant4 2.33.0 (latest release) without diracxx and encountered the following errors:

src/GlueXBeamConversionProcess.cc: In member function virtual double GlueXBeamConversionProcess::nucleonFormFactor(double, GlueXBeamConversionProcess::FormFactorType):
src/GlueXBeamConversionProcess.cc:1938:34: error: mProton was not declared in this scope
double tau = Q2_GeV / sqr(2 * mProton);
^
src/GlueXBeamConversionProcess.cc: In member function virtual double GlueXBeamConversionProcess::nuclearMass_GeV():
src/GlueXBeamConversionProcess.cc:2063:14: error: mNeutron was not declared in this scope
return mNeutron;
^
src/GlueXBeamConversionProcess.cc:2065:14: error: mProton was not declared in this scope
return mProton;

These are defined properly in Diracxx but if one wants to build without, they are not and this case is not caught by the compiler flags. As a simple workaround for now I added these to constants to the header file, but maybe you want a more elegant solution.