Scheduler fixes (PR17808)

[Paolo Carlini]

Steven Bosscher wrote:

>There are two new failures
>on ia64, because of assembler warnings:
>
>/tmp/ccBDW5xy.s: Assembler messages:
>/tmp/ccBDW5xy.s:186: Warning: Additional NOP may be necessary to workaround Itanium processor A/B step errata
>  
>
Weird: Andreas Schwab took care of that a while ago, by adding specific
DejaGNU code to the various prune.exp. Why isn't working for you?!?

Paolo.