ICC apparently optimises 0 * anything directly to zero, even when it
should be doing a multiplication to conform to IEEE requirements. GCC in
fast-math mode does the same, but that also makes the rest of the
function unreliable, so we try to turn off fast-math mode if we can.
Task-number: QTBUG-22340
Change-Id: I0e3c5f4927b0a6bcb3189bb156c18843fc4b29b9
Reviewed-by: Caroline Chao <caroline.chao@digia.com>
928fc8d939