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/compile/compile-loc2c.c

@@ -675,7 +675,7 @@ do_compile_dwarf_expr_to_c (int indent, string_file *stream,
       uint64_t uoffset, reg;
       int64_t offset;
 
-      print_spaces (indent - 2, stream);
+      stream->printf ("%*s", indent - 2, "");
       if (info[op_ptr - base].label)
 	{
 	  print_label (stream, scope, op_ptr - base);