netperf: patch to work-around partial alarm() functionality

In some cases netperf relies on SIGALRM to wake sleeping
send*/recv*() calls. alarm() API on OSv doesn't fully comply to
specification, i.e. it executes SIGALRM handler but doesn't
interrupt sleeping syscalls. Because of this there is a race
condition that makes netserver sleep infinitely in some cases.

This commit introduces patch for netperf that acts as a work-around
for this problem by setting socket timeout for network operations.

This commit also introduces simple script that builds patched netperf
in automated manner.

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>