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

ui/gfx/gfx.gyp

@@ -445,6 +445,12 @@
           '<(DEPTH)/build/linux/system.gyp:dridrm',
           ],
         }],
+        ['desktop_linux==1 or chromeos==1', {
+          'dependencies': [
+            # font_render_params_linux.cc uses fontconfig
+            '<(DEPTH)/build/linux/system.gyp:fontconfig',
+          ],
+        }],
       ],
       'target_conditions': [
         # Need 'target_conditions' to override default filename_rules to include