[PATCH 3.4] Warn for always-false bitwise ands

[Neil Booth]

John Levon wrote:-

> 	warn_boolean_bitwise_and.
> 
> 	* c-common.h (boolean_value_p): New. Declare
> 	warn_boolean_bitwise_and.
> 
> 	* c-opts.c (COMMAND_LINE_OPTIONS): Add
> 	-Wboolean-bitwise-and.
> 	(c_common_decode_option): Add to -Wall.
> 	[OPT_Wboolean_bitwise_and]: Handle.

I just want to question whether having YAO is a good idea.
Why not have the controlling variable set by -Wall like you do?

If the need comes in the future to really have a separate option,
it's trivial to add one.

Neil.