$NetBSD$

--- third_party/dav1d/BUILD.gn.orig	2020-07-15 18:56:49.000000000 +0000
+++ third_party/dav1d/BUILD.gn
@@ -113,7 +113,7 @@ if (is_win) {
   if (is_mac) {
     dav1d_copts += [ "-D_DARWIN_C_SOURCE" ]
   }
-  if (is_linux || is_android || current_os == "aix") {
+  if (is_linux || is_android || current_os == "aix" || is_bsd) {
     if (!is_clang) {
       dav1d_copts += [ "-D_GNU_SOURCE" ]
     }