feat: introduce onUsr2 and onUsr1

user/nicetarget.c

@@ -0,0 +1,35 @@
+#include "ulib.h"
+
+/*
+ * Only ever spawned by nicetest.c, with no argv at all -- same "*test /
+ * *target" shape cwdtest.c/cwdtarget.c already has. Sleeps immediately so
+ * nicetest.c gets a real window to renice it from the OUTSIDE while it is
+ * genuinely Sleeping, not just Runnable -- proving sysNice (syscall.c)
+ * reaches a blocked target, not only one that happens to be running right
+ * now. 4096 is an arbitrary but SHARED magic weight, agreed with
+ * nicetest.c's own renice call the same way herestest.c/the real shell
+ * agree on the literal string "hs-ok" -- no header constant ties the two
+ * together, the number is just repeated on both sides.
+ */
+
+int main(void)
+{
+    print("nicetarget: start, pid=");
+    printDec(userGetpid());
+    print("\n");
+    print("nicetarget: ready, sleeping before priority self-check\n");
+
+    userSleep(200);
+
+    long weight = userGetPriority(0);
+    print("nicetarget: own weight after sleep=");
+    printDec(weight);
+    print("\n");
+    if (weight != 4096) {
+        print("nicetarget: FAIL expected reniced weight 4096\n");
+        return 1;
+    }
+    print("nicetarget: reniced-while-sleeping-ok\n");
+
+    return 0;
+}