[DependenceInfo] Remove dead initialization. NFC.

Fix scan-analyzer issue:
Value stored to 'WARMemAccesses' during its initialization is never read

Patch by Dominik Adamski <adamski.dominik@gmail.com>

Signed-off-by: Dominik Adamski <adamski.dominik@gmail.com>

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@361196 91177308-0d34-0410-b5e6-96231b3b80d8