To take your own life is different than giving your life. If I was to take my own life, I would use a handgun most likely and shoot myself. If I was to put myself in harm's way to save others from being harmed, I would be giving my life.
Many believe Jesus was overpowered and taken by force, but they could not take Him by force. They had tried many times before to take Him that way, but the only way they could take Him was when He allowed them to.
Suicide is a sin. Thou shalt not kill (murder). Suicide is self-murder.