Revert "try O=1 on Jenkins"
Revert "try O=1 on Jenkins"

This reverts commit b57a718291d2449fcbcd8d88034f0106d4bde07c.

stan-dev/math,stan-dev/math,stan-dev/stan,stan-dev/math,stan-dev/math,stan-dev/stan,stan-dev/stan,stan-dev/math,stan-dev/math,stan-dev/stan,stan-dev/math,stan-dev/math,stan-dev/stan,stan-dev/math