Allocate space that may be accessed from C and FORTRAN
cnfRegp) for use from both C and FORTRAN.
This means that the returned pointer may subsequently be converted into a FORTRAN pointer of type
F77_POINTER_TYPE (using cnfFptr), and back into a C pointer (using cnfCptr). The contents of the
space may therefore be accessed from both languages. The allocated space should be freed using cnfFree when no longer required.