Support standard type 'bool'

[ascherer]

After my code declares

#include <stdbool.h>
...
typedef bool boolean;

splint common.c complains

common.h:36:14: Type boolean is probably meant as a boolean type, but the
    boolean type name is not set. Use -booltype boolean to set it.
  Use the -booltype, -boolfalse and -booltrue flags to change the name of the
  default boolean type. (Use -likelybool to inhibit warning)

and splint -booltype boolean common.c complains

common.h:36:14: Boolean type boolean defined using non-standard type bool
                   (integral, char or enum type expected)

Please add support for “non-standard standard type bool”.

[ascherer]

Note to self: This may be a user error, fixable by setting some command-line flags. stdbool.h seems to be used in splint already.

[rillig]

I don't think this is a user error. The intention of the code is very clear, therefore no additional command line option should be necessary. The option -booltype was useful before C99 to specify which of the many typedefs for int or unsigned char was meant to be a boolean type, and back then, that was useful.

[cooljeanius]

This kinda ties in with bug #12