towire: remove useless double-invert in towire_bool.

GCC optimizes it out anyway: I sent an uninitialized var and it sent 8!
The receiver checks the value is 0 or 1 anyway.

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

wire/towire.c

@@ -40,7 +40,7 @@ void towire_u64(u8 **pptr, u64 v)
 
 void towire_bool(u8 **pptr, bool v)
 {
-	u8 val = !!v;
+	u8 val = v;
 	towire(pptr, &val, sizeof(val));
 }