Linux: switch to using pkg-config for unbundled ICU

This was recommended by upstream ICU developer in https://ssl.icu-project.org/trac/ticket/6102
and should avoid issues with contaminated flags in icu-config.

BUG=none
R=thestig@chromium.org

Review URL: https://codereview.chromium.org/26723003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228979 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228979
Disable QUIC version 11 to avoid negotiation bugs

R=jar@chromium.org

Review URL: https://codereview.chromium.org/27507003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228980 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228980