unarr: merge fast and non-fast inflate code paths

git-svn-id: http://sumatrapdf.googlecode.com/svn/trunk/ext/unarr@9602 841c7e00-0c1d-0410-a694-8ba26473ccb1
unarr: further clean up inflate.c

git-svn-id: http://sumatrapdf.googlecode.com/svn/trunk/ext/unarr@9603 841c7e00-0c1d-0410-a694-8ba26473ccb1