They already know:
https://bitcointalksearch.org/topic/m.10541205
Topic: Update FAILED: 0.93 failed on Ubuntu 12.04 64-bit (Dependency libstdc++6 {>=4.7) (Read 2019 times)
February 24, 2015, 11:23:47 AM
February 24, 2015, 08:35:32 AM
The issue is that the Armory binary is expecting version 4.7 or above, but Ubuntu 12.04 only has 4.6.3. It does appear to be a mistake since they do list 12.04+ as being supported. Hopefully they'll see this and fix it. Even better would probably be for you to file a ticket at support.bitcoinarmory.com so they will definitely be aware of this issue.
February 24, 2015, 07:59:37 AM
I tried to update from 0.92.3 to 0.93 on my Ubuntu 12.04 64-bit computer and rec'd the following message:
Dependency not satisfiable libstdc++6 (>=4.7)
Dependency not satisfiable libstdc++6 (>=4.7)
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