change to Fortran PetscTruth in petsc-dev

[Barry Smith]

    I have changed the definition of PetscTruth in Fortran in petsc- 
dev to
logical*4. This will require small changes in Fortran code, for example
if (flg .eq. PETSC_TRUE) would become if (flg)

For backward compatibility you can put a #define  
PETSC_FORTRAN_PETSCTRUTH_INT 1 into
PETSC_ARCH/conf/petscconf.h
    Barry