Makes MPIRUN modifiable via an environment variable and not just as an...

Makes MPIRUN modifiable via an environment variable and not just as an argument to the script. (Also adds documentation with --help)


Former-commit-id: 65ab9098c4fd505a9ad9266791adbd5226c8809b

configure.ac

@@ -112,6 +112,9 @@ if test "$enable_mpi" = "yes"; then
 fi
 AM_CONDITIONAL([HAVEMPI],[test $enable_mpi = "yes"])
 
+# Indicate that MPIRUN can be modified by an environement variable
+AC_ARG_VAR(MPIRUN, Path to the mpirun command if non-standard)
+
 # Need C99 and inline support.
 AC_PROG_CC_C99
 AC_C_INLINE