socat: Fix compilation when usleep is missing

usleep is a legacy function that was removed in POSIX-2008. uClibc-ng can
be configured to compile without it. if out the code as it's not used.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

net/socat/patches/100-usleep.patch

@@ -0,0 +1,18 @@
+--- a/sycls.c
++++ b/sycls.c
+@@ -1329,6 +1329,7 @@ unsigned int Sleep(unsigned int seconds) {
+    return retval;
+ }
+ 
++#if 0
+ /* obsolete by POSIX.1-2001 */
+ void Usleep(unsigned long usec) {
+    Debug1("usleep(%lu)", usec);
+@@ -1336,6 +1337,7 @@ void Usleep(unsigned long usec) {
+    Debug("usleep() ->");
+    return;
+ }
++#endif
+ 
+ #if HAVE_NANOSLEEP
+ unsigned int Nanosleep(const struct timespec *req, struct timespec *rem) {