[headless] Enable headless embedders to specify fonts.

build/args/headless.gn

 # GN args template for the Headless Chrome library
 #
 # Add import to arg.gn in out directory and run gn gen on the directory to use.
 # E.g. for out directory out/foo:
 # echo 'import("//build/args/headless.gn")' > out/foo/args.gn
 # gn gen out/foo
 #
 # Use gn args to add your own build preference args.
 
 use_ozone = true
 ozone_auto_platforms = false
 ozone_platform = "headless"
 ozone_platform_headless = true
 
 # Embed resource.pak into binary to simplify deployment.
 headless_use_embedded_resources = true
 
+# Expose headless bindings for freetype library bundled with Chromium.
+headless_fontconfig_utils = true
+
 # In order to simplify deployment we build ICU data file
 # into binary.
 icu_use_data_file = false
 
 # Use embedded data instead external files for headless in order
 # to simplify deployment.
 v8_use_external_startup_data = false
 
 enable_nacl = false
 enable_print_preview = false
 enable_remoting = false
 use_alsa = false
 use_ash = false
 use_cups = false
 use_dbus = false
 use_gconf = false
 use_gio = false
 use_kerberos = false
 use_libpci = false
 use_pulseaudio = false
 use_udev = false