add new testcase for bind

With
0fb44559ffd6 af_unix: move unix_mknod() out of bindlock
the behavior of bind() for STREAM UNIX sockets changed in case a socket that is already bound is passed to bind() again.

This testcase fails for the new behavior and passes for the old one.

---

Changes to v2:
change to relative socket path and letting the harness handle the temporaty directory

Changes to v1:
I just cleaned the includes and comments as suggested.

---
 runtest/syscalls                          |  1 +
 testcases/kernel/syscalls/bind/.gitignore |  1 +
 testcases/kernel/syscalls/bind/bind03.c   | 81 +++++++++++++++++++++++
 3 files changed, 83 insertions(+)
 create mode 100644 testcases/kernel/syscalls/bind/bind03.c

index dc72484cb..e8b93a65b 100644
@@ -29,6 +29,7 @@ asyncio02 asyncio02
 
 bind01 bind01
 bind02 bind02
+bind03 bind03
 
 bdflush01 bdflush01
 

index ba46f4fa2..4ebea9ee7 100644
@@ -1,2 +1,3 @@
 /bind01
 /bind02
+/bind03

2.18.0

Hi Michael,

Pushed (with slightly changed commit message), thanks!

Kind regards,
Petr