Suppress warning on VS2017.

warning C4505: unreferenced local function has been removed

Bug: gn:48
Change-Id: Ib257a531d9a081945679853c15c0ecdec952e9a6
Reviewed-on: https://gn-review.googlesource.com/c/3960
Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Scott Graham <scottmg@chromium.org>

build/gen.py

diff --git a/build/gen.py b/build/gen.py
index 96dafb9..a7142fa 100755
--- a/build/gen.py
+++ b/build/gen.py
@@ -364,6 +364,7 @@
         '/wd4127',
         '/wd4244',
         '/wd4267',
+        '/wd4505',
         '/wd4838',
         '/wd4996',
     ])