Mozilla shouldn't force -O2 optimisation on user

[Maxim Sobolev]

Hi,

I think that every concept of "WITHOUT_OPTIMIZE" added in
rev.1.136 of ports/www/mozilla/Makefile is wrong. No port
should force optimisation level on user - we have CFLAGS
for this and each user should be able to select any
performance/stability ratio he wants.

IMO relevant part of 1.136 should be backed out, or possibly
turned into WITH_OPTIMIZED instead.

Thanks!

-Maxim