Add basic tools

tools/umount.c

@@ -0,0 +1,16 @@
+#include <stdio.h>
+#include <sys/mount.h>
+
+int main(int argc, char** argv) {
+    if (argc < 2) {
+        fprintf(stderr, "usage: %s <target>\n", argv[0]);
+        return 2;
+    }
+
+    if (unmount(argv[1], 0) != 0) {
+        perror("umount");
+        return 1;
+    }
+
+    return 0;
+}