Fix GN PDFium build when building all.

third_party/BUILD.gn

 # Copyright 2014 PDFium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 group("third_party") {
   deps = [
     ":bigint",
     ":freetype",
     ":safemath",
   ]
@@ skipping 18 matching lines @@
     "bigint/BigUnsignedInABase.cc",
   ]
 }
 
 static_library("freetype") {
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [
       "//third_party/pdfium:pdfium_config",
       "//build/config/compiler:no_chromium_code",
   ]
+  defines = [ "FT2_BUILD_LIBRARY" ]
   sources = [
     "freetype/include/freetype.h",
     "freetype/include/ft2build.h",
     "freetype/include/ftmm.h",
     "freetype/include/ftotval.h",
     "freetype/include/ftoutln.h",
     "freetype/include/tttables.h",
     "freetype/include/internal/ftobjs.h",
     "freetype/include/internal/ftstream.h",
     "freetype/include/internal/tttypes.h",
@@ skipping 29 matching lines @@
     "logging.h",
     "macros.h",
     "template_util.h",
     "numerics/safe_conversions.h",
     "numerics/safe_conversions_impl.h",
     "numerics/safe_math.h",
     "numerics/safe_math_impl.h",
   ]
 }