Use gyp targets to link in X11 libraries instead of setting -lXfoo
This sets up gyp targets for the various X11 libraries we use and uses
pkg-config to determine the correct cflags/ldflags incantations to use to
link against them instead of listing out -lXfoo lines in libraries sections
in gyp targets throughout the tree. This is more likely to generate the right
lines and makes the dependencies a bit more explicit.
BUG=339518
Review URL: https://codereview.chromium.org/
153223002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248939 0039d316-1c4b-4281-b951-d872f2087c98