Bug 1526509 - Remove lib32-libstdc++5 requirement from mozboot/archlinux.py. r=glandium

lib32-libstdc++5 moved from multilib to AUR, but it seems like we don't
need this anymore anyway.

Differential Revision: https://phabricator.services.mozilla.com/D19276

--HG--
extra : moz-landing-system : lando

python/mozboot/mozboot/archlinux.py

@@ -70,7 +70,6 @@ class ArchlinuxBootstrapper(NodeInstall, StyloInstall,
         # For downloading the Android SDK and NDK.
         'wget',
         # See comment about 32 bit binaries and multilib below.
-        'multilib/lib32-libstdc++5',
         'multilib/lib32-ncurses',
         'multilib/lib32-readline',
         'multilib/lib32-zlib',