Rename _const functions to use overloading instead

This renames a few functions -- skip_spaces_const,
skip_to_space_const, get_number_const, extract_arg_const -- to drop
the "_const" suffix and instead rely on overloading.

This makes future const fixes simpler by reducing the number of lines
that must be changed.  I think it is also not any less clear, as all
these functions have the same interface as their non-const versions by
design.  Furthermore there's an example of using an overload in-tree
already, namely check_for_argument.

This patch was largely created using some perl one-liners; then a few
fixes were applied by hand.

ChangeLog
2017-09-11  Tom Tromey  <tom@tromey.com>

	* common/common-utils.h (skip_to_space): Remove macro, redeclare
	as function.
	(skip_to_space): Rename from skip_to_space_const.
	* common/common-utils.c (skip_to_space): New function.
	(skip_to_space): Rename from skip_to_space_const.
	* cli/cli-utils.h (get_number): Rename from get_number_const.
	(extract_arg): Rename from extract_arg_const.
	* cli/cli-utils.c (get_number): Rename from get_number_const.
	(extract_arg): Rename from extract_arg_const.
	(number_or_range_parser::get_number): Use ::get_number.
	* aarch64-linux-tdep.c, ada-lang.c, arm-linux-tdep.c, ax-gdb.c,
	break-catch-throw.c, breakpoint.c, cli/cli-cmds.c, cli/cli-dump.c,
	cli/cli-script.c, cli/cli-setshow.c, compile/compile.c,
	completer.c, demangle.c, disasm.c, findcmd.c, linespec.c,
	linux-tdep.c, linux-thread-db.c, location.c, mi/mi-parse.c,
	minsyms.c, nat/linux-procfs.c, printcmd.c, probe.c,
	python/py-breakpoint.c, record.c, rust-exp.y, serial.c, stack.c,
	stap-probe.c, tid-parse.c, tracepoint.c: Update all callers.

gdb/stack.c

@@ -1285,7 +1285,7 @@ parse_frame_specification (const char *frame_exp, int *selected_frame_p)
 	  const char *p;
 
 	  /* Skip leading white space, bail of EOL.  */
-	  frame_exp = skip_spaces_const (frame_exp);
+	  frame_exp = skip_spaces (frame_exp);
 	  if (!*frame_exp)
 	    break;