Add grabber module

(cherry picked from commit b768d5648c)
Signed-off-by: Egor Savkin <es@m-labs.hk>

src/runtime/src/main.rs

@@ -123,7 +123,9 @@ mod grabber {
             delay(&mut countdown, Milliseconds(200)).await;
         }
     }
-}static mut LOG_BUFFER: [u8; 1<<17] = [0; 1<<17];
+}
+
+static mut LOG_BUFFER: [u8; 1<<17] = [0; 1<<17];
 
 #[no_mangle]
 pub fn main_core0() {