Add g++ multilib package to list of packages for building x86-32 on Trusty
Add g++ multilib package to list of packages for building x86-32 on Trusty

g++-4.8-multilib depends on a bunch of 32-bit headers and libraries (e.g.
libstdc++) needed to build NaCl

R=kschimpf@google.com
BUG=none

Review URL: https://codereview.chromium.org/1119103003

cohortfsllc/cohort-cocl2-sandbox,cohortfsllc/cohort-cocl2-sandbox,cohortfsllc/cohort-cocl2-sandbox,cohortfsllc/cohort-cocl2-sandbox,cohortfsllc/cohort-cocl2-sandbox,cohortfsllc/cohort-cocl2-sandbox