[testsuite] ARM tests should ignore warning about conflicting switches

[Mike Stump]

On Jun 14, 2011, at 10:47 AM, Janis Johnson wrote:
> Many tests in gcc.target/arm that specify "-march=" fail compilation
> when multilib flags include "-mcpu=" due to warnings about conflicts in
> switches, but then go on to pass the remainder of the test.

> OK for trunk and 4.6?

Ok.  As usual, please wait for any trunk fallout before committing to 4.6.