syscalls: implement sysctl and add process listing

kernel-src/sys/ctl/sysctl.c

@@ -0,0 +1,15 @@
+#include <kernel/sysctl.h>
+#include <errno.h>
+
+// oldp, old_lenp and newp might be user pointers
+int sysctl(const int *name, size_t name_len, void *oldp, size_t *old_lenp, void *newp, size_t new_len) {
+	if (name_len < 2 || name_len > SYS_CTL_NAME_MAX)
+		return EINVAL;
+
+	switch (*name) {
+		case SYS_CTL_KERN:
+			return sysctl_kern(name + 1, name_len - 1, oldp, old_lenp, newp, new_len);
+		default:
+			return EINVAL;
+	}
+}