hostlist: let hostlist_get_base() depend on current dimensions

This patch saves one call to slurmdb_setup_cluster_dims(): exploiting
that the dimensions for which hostlist_get_base() is called are known
in all contexts in which the function is used.

hostlist: shorter conversion

This replaces the hostlist_parse_int_to_array() routine with a simpler and 
equivalent routine. I was wondering what the algorithm does, when suddenly
the flow became simpler.

Problem: we want to create an array 'out' of 'dims' dimensions where
         out[i], 0 <= i < dims, has the coefficients a_j of the polynomial

	 a_(dims-1) * B^(dims-1) + ... + a_1 * B + a_0

	 where B is the base of the polynomial 'in' and
	    a_0        = out[dims - 1]
	    a_1        = out[dims - 2]
	    ...
	    a_(dims-1) = a[0]

Using the Horner Scheme, 'in' is represented as
 * dims = 1:                                   a_0 = out[0]
 * dims = 2:                        a_1  * B + a_0 = out[0] * B + out[1]
 * dims = 3:            (a_2  * B + a_1) * B + a_0 
 * dims = 4: ((a_3 * B + a_2) * B + a_1) * B + a_0
   ...
 * dims = n: ((a_(n-1) * B + a_(n-2)) * B ... + a_1) * B + a_0

We can get a_0 = out[dims-1] as "in % B" and then derive a_1, a_2, ... by
first dividing by B, and then repeating the process.

If in is 0, all 'dims' coefficients are 0, if it is negative, all coefficients
are negative.

Added that when a slurmctld closes the connection to the database it's registered host and port are removed.

added semi-support for cgywin systems.  The slurmctld doesn't work becuase it exports symbols to the dll's and dll'
s can't import things like that.  But things should compile correctly and user tools like sview appear to work corr
ectly.

OK, this will probably where this part of the project stops since I can't figure out how to have the dll's in windo
ws grab the symbols from the slurmctld (like part_list).  It just uses the private value which isn't what we want.
 Things like sview and such work fine though.  (In cygwin the slurmd gets the name in all uppercase so you have to define it that way)