8002116: This JdbReadTwiceTest.sh gets an exit 1

Explicitly check readability of file in question

Reviewed-by: sla, dholmes, olagneau

jdk/test/com/sun/jdi/JdbReadTwiceTest.sh

@@ -213,7 +213,14 @@ if [ ! -r c:/ ] ; then
     # If the file exists, we try to read it.  The
     # read will fail.
     mkFiles $HOME/jdb.ini
+    id > $HOME/jdb.ini
     chmod a-r $HOME/jdb.ini
+    if grep -q "uid=" $HOME/jdb.ini  ; then
+      echo "Unable to make file unreadable, so test will fail. chmod: $HOME/jdb.ini"
+      if grep -q "uid=0" $HOME/jdb.ini  ; then
+        echo "The test is running as root. Fix infrastructure!"
+      fi	
+    fi  
     doit
     failIfNot 1 "open: $HOME/jdb.ini"
     clean