The following patch helps in the case when a sockets library is installed; in my case, ls080b.zip from the DJGPP site:

=== modified file 'src/msdos.c'
--- src/msdos.c    2014-08-09 16:12:33 +0000
+++ src/msdos.c    2014-08-09 21:51:56 +0000
@@ -4016,7 +4017,7 @@
 #endif
 
 
-#ifndef HAVE_SELECT
+#ifndef HAVE_SYS_SELECT_H
 #include "sysselect.h"
 
 /* This yields the rest of the current time slice to the task manager.