lzop: add overflow check

See CVE-2014-4607
http://www.openwall.com/lists/oss-security/2014/06/26/20

function                                             old     new   delta
lzo1x_decompress_safe                               1010    1031     +21

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
(cherry picked from commit a9dc7c2f59dc5e92870d2d46316ea5c1f14740e3)