The libmpi_*.la fortran libraries make some direct calls to
libopen-pal.la. In many (most?) cases, having libmpi_* link
against libmpi is sufficient (because libmpi pulls in libopen-pal).
But when building RPMs on SLES, some compiler/linker flags are used
that seem to make this implicit linking not sufficient -- we get
missing opal symbols when creating libmpi_mpifh.la. So link in
open-pal directly (vs. indirectly), which solves the problem.