message.rs: resolve "should return bool" TODOs

src/dc_mimefactory.rs

@@ -39,7 +39,7 @@ pub struct dc_mimefactory_t<'a> {
     pub loaded: dc_mimefactory_loaded_t,
     pub msg: Message,
     pub chat: Option<Chat>,
-    pub increation: libc::c_int,
+    pub increation: bool,
     pub in_reply_to: *mut libc::c_char,
     pub references: *mut libc::c_char,
     pub req_mdn: libc::c_int,
@@ -102,7 +102,7 @@ pub unsafe fn dc_mimefactory_load_msg(
         loaded: DC_MF_NOTHING_LOADED,
         msg,
         chat: Some(chat),
-        increation: 0,
+        increation: false,
         in_reply_to: ptr::null_mut(),
         references: ptr::null_mut(),
         req_mdn: 0,
@@ -290,7 +290,7 @@ pub unsafe fn dc_mimefactory_load_mdn<'a>(
         loaded: DC_MF_NOTHING_LOADED,
         msg,
         chat: None,
-        increation: 0,
+        increation: false,
         in_reply_to: ptr::null_mut(),
         references: ptr::null_mut(),
         req_mdn: 0,