vmstat: Always emit a space after the free-memory column

When displaying in non-human form, if the free-memory number
is large (more than 7 digits), there is no space between it and
the page fault column.

PR:		221290
Submitted by:	Josuah Demangeon <mail@josuah.net> (Original version)

usr.bin/vmstat/vmstat.c

@@ -832,6 +832,7 @@ dovmstat(unsigned int interval, int reps)
 			xo_emit(" ");
 			xo_emit("{:free-memory/%7d}",
 			        vmstat_pgtok(total.t_free));
+			xo_emit(" ");
 		}
 		xo_emit("{:total-page-faults/%5lu} ",
 		        (unsigned long)rate(sum.v_vm_faults -