[analyzer] BasicConstraintManager: drop NE-constraints once we have a value.

This could conceivably cut down on state proliferation, although we don't
use BasicConstraintManager by default anymore. No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156362 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed