Fix bug in inlining of empty for() initializer

It was causing an exception. Fixed now.

Thanks to Cindy Reynaud for reporting the problem and sending a backtrace.

unit_tests/regression.suite/inliner-for-bug.lsl

@@ -0,0 +1,10 @@
+default
+{
+    state_entry()
+    {
+        for (; llSetRegionPos(<0,0,2>); llSleep(3))
+        {
+            llSleep(4);
+        }
+    }
+}

unit_tests/regression.suite/inliner-for-bug.out

@@ -0,0 +1,15 @@
+default
+{
+    state_entry()
+    {
+        @___for__00001;
+        if (llSetRegionPos(<0, 0, 2>))
+        {
+            {
+                llSleep(4);
+            }
+            llSleep(3);
+            jump ___for__00001;
+        }
+    }
+}

unit_tests/regression.suite/inliner-for-bug.run

@@ -0,0 +1 @@
+main.py -y -O clear,inline -