Updated flex packages fix security vulnerability

It was found that flex incorrectly resized the num_to_read variable in yy_get_next_buffer. The buffer is resized if this value is less or equal to zero. With special crafted input it is possible, that the buffer is not resized if the input is larger than the default buffer size of 16k. This allows a heap buffer overflow. It may be possible to exploit this remotely, depending on the application that is built using flex (CVE-2016-6354). Note that any affected applications would need to be rebuilt with the updated flex to fully fix this issue.