Add missing fontconfig dependency to ui/gfx

We're using fontconfig in font_render_params_linux.cc without declaring a
depedency. This fixes the "Ozone ECS Linux" build.

TEST=build ui_unittests with "embedded==1 component=shared_library"
TBR=asvitkine@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/133973004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247965 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247965