relax the cimbare_encode() bufize check to allow multiples of chunk size

There's no reason not to allow this, and it gives us more flexibility
(ex: maybe the caller wants 128k buffers instead of 16k)

Author: sz3

src/lib/cimbar_js/cimbar_js.cpp

@@ -178,7 +178,7 @@ int cimbare_encode(const unsigned char* buffer, unsigned size)
 		if (!_comp->write(reinterpret_cast<const char*>(buffer), size))
 			return -2;
 	}
-	if (size == cimbare_encode_bufsize())
+	if (size%cimbare_encode_bufsize() == 0 and size != 0)
 		return 1; // more to do
 
 	// otherwise, we're ready