Update memcheck.supp, add a new suppression rule for 32bit ubuntu

[skip ci]
Update ubuntu-12.04-detailed.md

- add ppa to install latest version of cmake. old version which came with ubuntu-12.04 has a problem with valgrind.
[skip ci]
Fix bug in ho_unifier

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Remove cleanup_subst. The residue may still reference auxiliary variable. So, it is not safe to remove then from the resultant partial substitution.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add imitation step for equalities.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add imitation for lambdas and Pis

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>