Set build flag when using own FreeType.

Set the SK_FREETYPE_MINIMUM_RUNTIME_VERSION build flag when the
use_system_freetype gn flag is false. Currently the build flag is only
set when is_win or is_mac, but this needs to be set any time it is
known that FreeType will be built into the resulting binary. In
particular this is desired for Android and WebView, but also for
desktop Linux.

BUG=chromium:715429

Change-Id: Ie5e425b0b347caf51400c5522a42e8a88605c147
Reviewed-on: https://chromium-review.googlesource.com/524185Reviewed-by: Dominik Röttsches <drott@chromium.org>
Reviewed-by: Ben Wagner <bungeman@chromium.org>
Commit-Queue: Ben Wagner <bungeman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478644}

skia/BUILD.gn

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
+import("//build/config/freetype/freetype.gni")
 import("//build/config/ui.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//printing/features/features.gni")
@@ -53,7 +54,7 @@ config("skia_config") {
     defines += [ "SK_HAS_JPEG_LIBRARY" ]
   }
 
-  if (is_win || is_mac) {
+  if (!use_system_freetype) {
     defines += [ "SK_FREETYPE_MINIMUM_RUNTIME_VERSION=(((FREETYPE_MAJOR) * 0x01000000) | ((FREETYPE_MINOR) * 0x00010000) | ((FREETYPE_PATCH) * 0x00000100))" ]
   }