Add -Wno-write-strings

This is being turned on in the main repo.

Change-Id: I6df12cd17a139000e0bd788b773626a25fe37001
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/glfw/+/576487
Reviewed-by: Shai Barack <shayba@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index 98b79ec..c0eb97b 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -14,10 +14,11 @@
 
   # add flags to avoid compiler warnings
   cflags += [
-    "-Wno-int-conversion",
     "-Wno-implicit-function-declaration",
+    "-Wno-int-conversion",
     "-Wno-missing-field-initializers",
     "-Wno-sign-compare",
+    "-Wno-write-strings",
   ]
 }
 static_library("glfw") {