baremetal: build userland/ programs using baremetal path property instead of symlinks

Otherwise I'll go crazy with symlink action.

userland/c/return0.c

@@ -0,0 +1,6 @@
+/* false.c is a superset of this, this is mainly a sanity check for
+ * baremetal where we don't have CLI arguments yet:
+ * https://github.com/cirosantilli/linux-kernel-module-cheat/issues/67
+ */
+
+int main(void) { return 0; }