Fix Visual Studio build from GN generated files

VS does not like to see <, > in the XML nodes of the build files.  Work
around this issue by replacing less-than and greater-than characters in
the FreeType custom config include file path definitions with escaped
quotes.

BUG=pdfium:701

Change-Id: I879ade670158ccb4d435b65cde382c6e6b32e002
Reviewed-on: https://pdfium-review.googlesource.com/4330
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/third_party/BUILD.gn b/third_party/BUILD.gn
index c270a10..7730212 100644
--- a/third_party/BUILD.gn
+++ b/third_party/BUILD.gn
@@ -64,8 +64,11 @@
       "//third_party/freetype/src/include",
     ]
     defines = [
-      "FT_CONFIG_MODULES_H=<freetype-custom-config/ftmodule.h>",
-      "FT_CONFIG_OPTIONS_H=<freetype-custom-config/ftoption.h>",
+      # GN currently does not escape '<' and '>' when generating xml based
+      # Visual Studio project files. As a result, use quotes instead of pointy
+      # brackets in these defines.
+      "FT_CONFIG_MODULES_H=\"freetype-custom-config/ftmodule.h\"",
+      "FT_CONFIG_OPTIONS_H=\"freetype-custom-config/ftoption.h\"",
     ]
   }