Fix the build on Emscripten struct timeval is used in this file, which requires <sys/time.h> to be included.
diff --git a/src/netops.c b/src/netops.c
index 73375d7..0f85eae 100644
--- a/src/netops.c
+++ b/src/netops.c
@@ -8,6 +8,7 @@
# include <sys/types.h>
# include <sys/socket.h>
# include <sys/select.h>
+# include <sys/time.h>
# include <netdb.h>
#else
# define _WIN32_WINNT 0x0501