Added a new F77EXTERNS option that fixed a Mac-specific problem with f77 name mangling.  This was done because of incompatibilities with PETSC/MPICH, and to make things work correctly, the following files were also changed:
Added a new F77EXTERNS option that fixed a Mac-specific problem with
f77 name mangling.  This was done because of incompatibilities with
PETSC/MPICH, and to make things work correctly, the following files
were also changed:

config/compiler/gcc-3.x-Darwin/config_f77.h: added F77EXTERNS_SOMETIMES_EXTRATRAILINGBAR
config/compiler/gcc-3.x-Darwin/f77.def: removed -fno-second-underscore from COMPILER_F77_FLAGS


geodynamics/lithomop,geodynamics/lithomop,geodynamics/lithomop,geodynamics/lithomop