opal-restart.c disables crs module selection by setting
crs_base_do_not_select to true using opal_setenv() before
opal_init(). After opal_init() it enables module selection
by changing the variable back to false using opal_setenv().
This does not work anymore as the variables are only read
from the environment during variable registration.
This changes the second opal_setenv() to mca_base_var_set_value()
This commit was SVN r31108.
62dea2be84