science/mbdyn: fix build on powerpc64*

In file included from bulk.cc:35:
In file included from ./dataman.h:47:
In file included from ./mbpar.h:107:
In file included from ./../../libraries/libmbutil/parsinc.h:108:
./../../libraries/libmbutil/parser.h:275:3: error: expected identifier

FIRSTARG,
^

/usr/include/machine/frame.h:112:18: note: expanded from macro 'FIRSTARG'

^

1 error generated.