Make linux/make build on travis faster.
Make linux/make build on travis faster.

We don't need superuser there.

ianhuang-777/guetzli,szabadka/guetzli,ianhuang-777/guetzli,ianhuang-777/guetzli,google/guetzli,ianhuang-777/guetzli,google/guetzli,guanzidashu/guetzli_ios_metal,szabadka/guetzli,dloeng/guetzli,guanzidashu/guetzli_ios_metal,google/guetzli,google/guetzli,guanzidashu/guetzli_ios_metal,szabadka/guetzli,dloeng/guetzli,dloeng/guetzli,guanzidashu/guetzli_ios_metal