Allow use of robust list syscalls

The set_robust_list syscall sets the list of futexes which are
cleaned up on thread exit, and are needed to avoid mutexes
being held forever on thread exit.

See for example in Musl libc mutex handling:
http://git.musl-libc.org/cgit/musl/tree/src/thread/pthread_mutex_trylock.c#n22

Signed-off-by: Justin Cormack <justin.cormack@unikernel.com>
Upstream-commit: 7b133e7235593f8d46832045da339395e71e8148
Component: engine

components/engine/daemon/execdriver/native/seccomp_default.go

@@ -85,12 +85,6 @@ var defaultSeccompProfile = &configs.Seccomp{
 			Action: configs.Errno,
 			Args:   []*configs.Arg{},
 		},
-		{
-			// Deny getting the list of robust futexes
-			Name:   "get_robust_list",
-			Action: configs.Errno,
-			Args:   []*configs.Arg{},
-		},
 		{
 			// Deny manipulation and functions on kernel modules.
 			Name:   "init_module",
@@ -267,12 +261,6 @@ var defaultSeccompProfile = &configs.Seccomp{
 			Action: configs.Errno,
 			Args:   []*configs.Arg{},
 		},
-		{
-			// Deny setting the list of robust futexes
-			Name:   "set_robust_list",
-			Action: configs.Errno,
-			Args:   []*configs.Arg{},
-		},
 		{
 			// Time/Date is not namespaced
 			Name:   "settimeofday",