Add ut_array_1d_int_set_id.

Added function ut_array_1d_int_set_id, which set the elements of a 1D
int array to their positions in the array.  The resulting values of the
array are: 0, 1, 2, etc.
Change ut_sys_runwtime.

Changed ut_sys_runwtime so that the program does not have to be
specified through the full path (a relative path also does).  This is
done by changing execv to execvp.