Revert 262747 "Improve GN public header file checking"

trunk/src/third_party/freetype2/BUILD.gn

Index: trunk/src/third_party/freetype2/BUILD.gn
===================================================================
--- trunk/src/third_party/freetype2/BUILD.gn	(revision 262754)
+++ trunk/src/third_party/freetype2/BUILD.gn	(working copy)
@@ -2,8 +2,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-assert(is_linux, "This file should only be depended on from Linux.")
-
 config("freetype2_config") {
   include_dirs = [ "include", "src/include" ]
 }