test: Fix use of syscall::execve:entry args[1][?]

Commit 8233237 ("proc: use a rawtp for the proc:::exit probe") included
some test changes.  Specifically, it sought to use syscall::execve:entry
probe arguments args[1][0] and args[1][1] to recognize "sleep 10000".
The patch recognized that the argv pointers in question were in user
space, requiring copyinstr() to access the strings.

But it's trickier than that.  The args[1][?] require two dereferencings,
both in user space.  So a copyin() is required to access args[1] and
then copyinstr() to access the args[1][?].

Fix the tests to use two layers of copyin*() to double dereference the
args[1][?] strings.

Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>

test/unittest/proc/tst.exitkilled.sh

@@ -12,8 +12,10 @@ script()
 {
 	$dtrace $dt_flags -s /dev/stdin <<EOF
 	syscall::execve:entry
-	/copyinstr((uintptr_t)args[1][0]) == "sleep" && args[1][1] &&
-	 copyinstr((uintptr_t)args[1][1]) == "10000"/
+	/(this->myargs = (uintptr_t *)copyin((uintptr_t)args[1], 2 * sizeof(char *)))
+	 && copyinstr(this->myargs[0]) == "sleep"
+	 && this->myargs[1]
+	 && copyinstr(this->myargs[1]) == "10000"/
 	{
 		kill_pid = pid;
 	}

test/unittest/proc/tst.signal.sh

@@ -12,8 +12,10 @@ script()
 {
 	$dtrace $dt_flags -s /dev/stdin <<EOF
 	syscall::execve:entry
-	/copyinstr((uintptr_t)args[1][0]) == "sleep" && args[1][1] &&
-	 copyinstr((uintptr_t)args[1][1]) == "10000"/
+	/(this->myargs = (uintptr_t *)copyin((uintptr_t)args[1], 2 * sizeof(char *)))
+	 && copyinstr(this->myargs[0]) == "sleep"
+	 && this->myargs[1]
+	 && copyinstr(this->myargs[1]) == "10000"/
 	{
 		sig_pid = pid;
 	}
@@ -23,12 +25,14 @@ script()
 	 sig_pid == args[1]->pr_pid && args[2] != SIGUSR1/
 	{
 		/* Wrong signal being sent. */
+		printf("wrong signal sent: %d vs %d\n", args[2], SIGUSR1);
 		exit(1);
 	}
 
 	proc:::signal-handle
 	/sig_pid == pid/
 	{
+		printf("signal received %d\n", args[0]);
 		exit(args[0] == SIGUSR1 ? 0 : 1);
 	}