www/lagrange: Make SSE4.1 support optional

Older class AMD64 and i386 CPUs do not support
SSE4.1, so make it opt-in instead. This is a
problem since a build host may support the
feature-set whilst a package consumer does not,
causing an unexpected crash upon starting
the application.

(cherry picked from commit 6a9dfe8760c745ce1710c71c797f88c2f5416b1c)