Anticholinergic medications are called this way because they block transmission via the neurotransmitter acetylcholine. To be more precise, there are different types of acetylcholine receptors: nicotinergic and muscarinergic acetylcholine receptors. What we refer to as anticholinergica are usually selective inhibitors of the muscarinergic receptors. By this, they inhibit parasymphatic transmition and this is why they are also called (maybe a better term) parasympatholytics.
Anti-histaminic drugs however block the various histamine receptors.
In principle, anticholinergic and antihistaminic drugs are separate agents. The most common anticholinergic drugs are atropine, butylscopalamine and scopolamine.
Atropine has a (very low) affinity for histamine receptors and could therefore be considered anti-histaminic; but I have not found references whether it actually has an effect on humans in vivo. I could not find anything related to scopolamine and butylscopalamine.
In clinical practice, anticholinergic drugs are not considered antihistaminic drugs, and vice versa antihistaminic drugs are not considered anticholinergic.