Rewrote nice handling to make more portable

scripts/safe_mysqld.sh

@@ -159,7 +159,12 @@ then
   NOHUP_NICENESS=`nohup nice 2>&1`
   if test $? -eq 0 && test x"$NOHUP_NICENESS" != x0 && nice --1 echo foo > /dev/null 2>&1
   then
-    NOHUP_NICENESS="nice -n $NOHUP_NICENESS nohup"
+    if $NOHUP_NICENESS -gt 0
+    then
+      $NOHUP_NICENESS="nice --$NOHUP_NICENESS nohup"
+    else
+      NOHUP_NICENESS="nice -$NOHUP_NICENESS nohup"
+    fi
   else
     NOHUP_NICENESS="nohup"
   fi