[INTERNAL] deleted AutoHashMap class

Was only used in one place and so is not worth the LOC is uses.

Change-Id: Ieaf480cc4310ca29663967b4cab3b822930f85a9
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1942
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>