ccan_tokenizer: switch example from grab_file to ccan/grab_file.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
ccan_tokenizer: remove warnings with gcc

/home/rusty/devel/cvs/ccan/ccan/ccan_tokenizer/test/run.c:898:66: warning: initialization discards ‘const’ qualifier from pointer target type [enabled by default]
 #define T(txt, ...) {txt, sizeof(txt)-1, array_count_pair(struct token, __VA_ARGS__)}
...

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
charset: make example use tal/grab_file instead of grab_file.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
tal/str: use tal/grab_file not grab_file in example.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>