C6X FP testcase fixes

[Mike Stump]

On Jul 15, 2011, at 4:09 AM, Bernd Schmidt wrote:
> This fixes a number of testsuite failures on C6X for targets with
> floating point hardware. The hardware has the following quirks:
> 
> * Divide is implemented using reciprocals; TI requested a default of
>  -freciprocal-math
> * Multiply, comparison and conversion instructions treat denormal
>  inputs as zero.
> 
> Ok?

Ok.  I'm hoping someone might have a more elegant way to handle gcc/testsuite/gcc.c-torture/execute/ieee/mzero2.c. I don't have any specific suggestion, which is why I'm approving it.  If someone has of a better way to handle it, feel free to check in a better version.  :-)  Watch for reviews by fp-type people...  I'd defer to them...