Don't redefine MSG_NOSIGNAL.
https://github.com/HaxeFoundation/neko/commit/b61b0fc55bc7a8b0ba54b1cf5a986c5a50b3d950
--- libs/common/socket.c.orig
+++ libs/common/socket.c
@@ -47,7 +47,7 @@
 #	define HANDLE_EINTR(x)	if( errno == EINTR ) goto x
 #endif
 
-#if defined(OS_WINDOWS) || defined(OS_MAC)
+#ifndef MSG_NOSIGNAL
 #	define MSG_NOSIGNAL 0
 #endif
 
--- libs/std/socket.c.orig
+++ libs/std/socket.c
@@ -61,7 +61,7 @@
 #	define EPOLLOUT 0x004
 #endif
 
-#if defined(NEKO_WINDOWS) || defined(NEKO_MAC)
+#ifndef MSG_NOSIGNAL
 #	define MSG_NOSIGNAL 0
 #endif