add opensuse-12.2 to os_support

os_support is not currently used by anything (BC_OS_SUPPORT is
populated in build_lib.sh from it but never used) but if it ever
gets used for anything, opensuse-12.2 should be in there.
Merge pull request #424 from aspiers/topic/opensuse-12.2-support

Merged by devtool for VictorLowther