Disable the -Wnewline-eof warning

We don't want to enforce this for third party code.

Change-Id: I804ce6a614f853b00000781ad4b5b8e116e465a7
diff --git a/BUILD.gn b/BUILD.gn
index 98baa5e..dd3173b 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -39,6 +39,7 @@
   cflags = [
     "-include",
     rebase_path("fuchsia/fuchsia-compat.h"),
+    "-Wno-newline-eof",
     "-Wno-pointer-sign",
   ]