"bogart" has nothing to do with Humphrey Bogart. All such definitions are merely passed along out of error. At Folsom prison in California the habit of putting your arm around the food to keep others from takin it was called "bowlguarding". From Folsom it spread to other prisons and into the general population. This expression compressed to "bogart" and perfectly extended to hogging a marijuana joint. It is a prison term and much precedes the 1976 song where it first became commonly heard generally outside of California.
Don't bogart that joint, my friend.