In an upcoming release, (we are targeting March 8th), we will be removing Ubuntu 10 and Ubuntu 12 from our Shared Object (SO) precompiled rule build system.
We have already added SO builds for Ubuntu 14, 16, and 17, in both 32bit and x64 to replace the older EOL'ed versions of Ubuntu.
Please provide us feedback here, or on the Snort-Sigs mailing list! Thank you!