Remove print_spaces

This removes the print_spaces helper function, in favor of using the
"*%s" idiom that's already used in many places in gdb.  One spot (in
symmisc.c) is changed to use print_spaces_filtered, because the rest
of that function is using filtered output.  (This highlights one way
that the printf idiom is better -- this error is harder to make when
using that.)

Regression tested on x86-64 Fedora 34.

gdb/utils.c

@@ -779,12 +779,6 @@ uinteger_pow (ULONGEST v1, LONGEST v2)
     }
 }
 
-void
-print_spaces (int n, struct ui_file *file)
-{
-  fputs_unfiltered (n_spaces (n), file);
-}
-
 /* Print a host address.  */
 
 void