disu2gncn1 variables are not allocated, passed, and deallocated correctly

[langevin-usgs]

In disu2gncn1.f the arrays allocated below are not always allocated, but they are always passed into subroutines below. This causes runtime problems and is not good from. Also these variables are not deallocated, so that is a problem too. This should be fixed in the next release.

C5------CALCULATE AMOUNT OF SPACE USED BY GNCn PACKAGE AND ALLOCATE GNCn.
      MXACTGNn = NGNCNPn+MXFBPn
      IGNCPBn = MXACTGNn + 1
      MXGNCn = MXACTGNn + MXFBPn
      ALLOCATE (GNCn(3+2*MXADJn,MXGNCn))
      IF(IFLALPHAn.EQ.1) ALLOCATE (SATCn(MXADJN+1,MXGNCn)) !STORES SATURATED CONDUCTANCES FOR COMPUTING CONTRIBUTING FACTORS
      IF(ISYMGNCn.EQ.0) ALLOCATE (IRGNCn(2,MXADJn,MXGNCn))
      IF(I2Kn.EQ.1) ALLOCATE (LGNCn(MXGNCn)) ! NEED TO ALSO STORE LAYER OF GNCn NODE AND NODAL TRANSMISSIVITY (OR S)

This shows up as an error when running the biscayne problem in debug mode with gfortran 7.x on linux, and perhaps other operating systems.