Current master is broken when configuring with SZ

Created by: williamfgc

the fortran_add_test_helper function doesn't handle the BPWriteReadSZ* tests in the operation subdirectory. The following message appears:

 Features:
    Library Type: shared
    Build Type:   Debug
    Testing: ON
    Build Options:
      Blosc    : ON
      BZip2    : ON
      ZFP      : OFF
      SZ       : ON
      MGARD    : ON
      PNG      : ON
      MPI      : ON
      DataMan  : OFF
      Table    : OFF
      SSC      : OFF
      SST      : ON
      DataSpaces: OFF
      ZeroMQ   : ON
      HDF5     : ON
      Python   : ON
      Fortran  : ON
      SysVShMem: ON
      Profiling: ON
      Endian_Reverse: OFF
    RDMA Transport for Staging: Unconfigured

-- Configuring done
CMake Error at testing/adios2/bindings/fortran/CMakeLists.txt:9 (add_executable):
  Cannot find source file:

    TestBPWriteReadSZ3D.F90

  Tried extensions .c .C .c++ .cc .cpp .cxx .cu .m .M .mm .h .hh .h++ .hm
  .hpp .hxx .in .txx
Call Stack (most recent call first):
  testing/adios2/bindings/fortran/CMakeLists.txt:76 (fortran_add_test_helper)


CMake Error at testing/adios2/bindings/fortran/CMakeLists.txt:9 (add_executable):
  Cannot find source file:

    TestBPWriteReadSZ2D.F90

  Tried extensions .c .C .c++ .cc .cpp .cxx .cu .m .M .mm .h .hh .h++ .hm
  .hpp .hxx .in .txx
Call Stack (most recent call first):
  testing/adios2/bindings/fortran/CMakeLists.txt:75 (fortran_add_test_helper)


CMake Error at testing/adios2/bindings/fortran/CMakeLists.txt:9 (add_executable):
  No SOURCES given to target: Test.Bindings.Fortran.BPWriteReadSZ3D
Call Stack (most recent call first):
  testing/adios2/bindings/fortran/CMakeLists.txt:76 (fortran_add_test_helper)


CMake Error at testing/adios2/bindings/fortran/CMakeLists.txt:9 (add_executable):
  No SOURCES given to target: Test.Bindings.Fortran.BPWriteReadSZ2D
Call Stack (most recent call first):
  testing/adios2/bindings/fortran/CMakeLists.txt:75 (fortran_add_test_helper)


CMake Generate step failed.  Build files cannot be regenerated correctly.