gdb: convert some function arguments from int to bool

gdb: convert some function arguments from int to bool

A little int to bool conversion around the 'watch' type commands.
There should be no user visible changes after this commit.

gdb/ChangeLog:

	* breakpoint.c (update_watchpoint): Pass 'false' not '0'.
	(watch_command_1): Update parameter types.  Convert locals to
	bool.
	(watch_command_wrapper): Change parameter type.
	(watch_maybe_just_location): Change locals to bool.
	(rwatch_command_wrapper): Update parameter type.
	(awatch_command_wrapper): Update parameter type.
	* breakpoint.h (watch_command_wrapper): Change parameter type.
	(rwatch_command_wrapper): Update parameter type.
	(awatch_command_wrapper): Update parameter type.
	* eval.c (fetch_subexp_value): Change parameter type.
	* ppc-linux-nat.c (ppc_linux_nat_target::check_condition): Pass
	'false' not '0'.
	* value.h (fetch_subexp_value): Change parameter type in
	declaration.