SkPDF: Add Sfntly to DEPS, gyp

Note: this can be disabled via:
    GYP_DEFINES='skia_pdf_use_sfntly=0

Warning: dm is 34% slower and uses 9% more memory.  This is
okay.

Motivation: We want to test this code path in DM, since it is
always used by Chromium and Android.

BUG=skia:3563

Committed: https://skia.googlesource.com/skia/+/6a53b04e26749ea61f690ece408f2a1c0a5ad5bb

Review URL: https://codereview.chromium.org/1134683006
diff --git a/gyp/sfntly.gyp b/gyp/sfntly.gyp
new file mode 100644
index 0000000..4e3ca5f
--- /dev/null
+++ b/gyp/sfntly.gyp
@@ -0,0 +1,55 @@
+# Copyright (c) 2011 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+{
+  'targets': [
+    {
+      'target_name': 'sfntly',
+      'type': 'static_library',
+      'includes': [
+        'common_conditions.gypi',
+        'common_variables.gypi',
+      ],
+      'variables': {
+        'sfntly_src_path': '../third_party/externals/sfntly',
+      },
+      'direct_dependent_settings': {
+        'include_dirs': [ '<(sfntly_src_path)/sample/chromium', ],
+        'defines': [
+          'SK_SFNTLY_SUBSETTER="font_subsetter.h"',
+        ],
+      },
+      'sources': [
+        '<(sfntly_src_path)/sample/chromium/font_subsetter.cc',
+        '<(sfntly_src_path)/sample/chromium/subsetter_impl.cc',
+        '<!@(python find.py ../third_party/externals/sfntly/sfntly "*.c*")'
+      ],
+      'include_dirs': [
+        '<(sfntly_src_path)',
+      ],
+      'defines': [
+        'SFNTLY_NO_EXCEPTION',
+      ],
+      'dependencies' : [
+        'icu.gyp:icuuc',
+      ],
+      'conditions': [
+        [ 'skia_os == "win"',
+          {
+            'defines': [ 'WIN32', ],
+            'msvs_settings': {
+              'VCCLCompilerTool': {
+                'AdditionalOptions': [ '/EHsc' ],
+              },
+            },
+          }
+        ],
+        [ 'skia_os in ["linux", "freebsd", "openbsd", "solaris", "chromeos"]',
+          { 'link_settings': { 'libraries': [ '-lpthread', ], }, },
+        ],
+      ],
+      # TODO(jschuh): http://crbug.com/167187
+      'msvs_disabled_warnings': [ 4267, 4244 ],
+    },
+  ]
+}