A 19-year-old man died after suffering multiple stab wounds outside a 7-Eleven convenience store in Jamaica Plain early yesterday morning, Boston police said. They found the man at 4:22 a.m. outside the store in Hyde Square, according to a statement. He was pronounced dead at Brigham and Women’s Hospital. The man’s name was being withheld pending notification of next of kin, according to Officer James Kenneally, a police spokesman. Police said an altercation preceded the stabbing but no other details were immediately available. Police asked anyone with information to call detectives at 617-343-4470, call the anonymous tip line at 800-494-TIPS, or text the word ‘TIP’ to CRIME (27463).