Kernel/LibC: Implement sigwait

userspace/libraries/LibC/include/sys/syscall.h

@@ -91,6 +91,7 @@ __BEGIN_DECLS
 	O(SYS_SIGPENDING,		sigpending)		\
 	O(SYS_SIGPROCMASK,		sigprocmask)	\
 	O(SYS_SIGSUSPEND,		sigsuspend)		\
+	O(SYS_SIGWAIT,			sigwait)		\
 	O(SYS_SETITIMER,		setitimer)		\
 	O(SYS_POSIX_OPENPT,		posix_openpt)	\
 	O(SYS_PTSNAME,			ptsname)		\

userspace/libraries/LibC/signal.cpp

@@ -169,3 +169,10 @@ int sigsuspend(const sigset_t* sigmask)
 {
 	return syscall(SYS_SIGSUSPEND, sigmask);
 }
+
+int sigwait(const sigset_t* __restrict set, int* __restrict sig)
+{
+	if (syscall(SYS_SIGWAIT, set, sig) == -1)
+		return errno;
+	return 0;
+}