selftests/net: Cover the IP_LOCAL_PORT_RANGE socket option

Exercise IP_LOCAL_PORT_RANGE socket option in various scenarios:

1. pass invalid values to setsockopt
2. pass a range outside of the per-netns port range
3. configure a single-port range
4. exhaust a configured multi-port range
5. check interaction with late-bind (IP_BIND_ADDRESS_NO_PORT)
6. set then get the per-socket port range

Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/Makefile

@@ -45,6 +45,7 @@ TEST_PROGS += arp_ndisc_untracked_subnets.sh
 TEST_PROGS += stress_reuseport_listen.sh
 TEST_PROGS += l2_tos_ttl_inherit.sh
 TEST_PROGS += bind_bhash.sh
+TEST_PROGS += ip_local_port_range.sh
 TEST_PROGS_EXTENDED := in_netns.sh setup_loopback.sh setup_veth.sh
 TEST_PROGS_EXTENDED += toeplitz_client.sh toeplitz.sh
 TEST_GEN_FILES =  socket nettest
@@ -76,6 +77,7 @@ TEST_PROGS += sctp_vrf.sh
 TEST_GEN_FILES += sctp_hello
 TEST_GEN_FILES += csum
 TEST_GEN_FILES += nat6to4.o
+TEST_GEN_FILES += ip_local_port_range
 
 TEST_FILES := settings