dcerpc: handles bigger inputs than 2^16

By comparing integers with the largest size

(cherry picked from commit 6f03ee2e47)

rust/src/dcerpc/dcerpc.rs

@@ -1050,7 +1050,7 @@ impl DCERPCState {
 
         let fraglen = self.get_hdr_fraglen().unwrap_or(0);
 
-        if (buffer.len() as u16) < fraglen {
+        if (buffer.len()) < fraglen as usize {
             SCLogDebug!("Possibly fragmented data, waiting for more..");
             self.extend_buffer(buffer, direction);
             return AppLayerResult::ok();