Not all libcs have support for tm_gmtoff which is only available for BSD
compatibility, and guarded with __USE_BSD defines, use __tm_gmtoff otherwise.
Signed-off-by: Florian Fainelli <florian@openwrt.org>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@34307 3c298f89-4303-0410-b956-a3cf2f4a3e73