Fix bug in tcu::Interval::intersects()
Fix bug in tcu::Interval::intersects()

This bug (probably just a typo) was causing issues in atan(y, x) tests.
The verification didn't account for small denormal divisors being
flushed to +0.

Bug: 21326633
Change-Id: I044ab38fb7f2ae316dfdac0674eab942fc5c8446

KhronosGroup/VK-GL-CTS,KhronosGroup/Vulkan-CTS,googlestadia/VK-GL-CTS,geekboxzone/mmallow_external_deqp,KhronosGroup/VK-GL-CTS,googlestadia/VK-GL-CTS,KhronosGroup/Vulkan-CTS,geekboxzone/mmallow_external_deqp,KhronosGroup/VK-GL-CTS,geekboxzone/mmallow_external_deqp,chadversary/deqp,KhronosGroup/Vulkan-CTS,googlestadia/VK-GL-CTS,KhronosGroup/VK-GL-CTS,chadversary/deqp,geekboxzone/mmallow_external_deqp,chadversary/deqp,googlestadia/VK-GL-CTS,chadversary/deqp,googlestadia/VK-GL-CTS,KhronosGroup/VK-GL-CTS,chadversary/deqp,geekboxzone/mmallow_external_deqp,chadversary/deqp,googlestadia/VK-GL-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/VK-GL-CTS,KhronosGroup/Vulkan-CTS,geekboxzone/mmallow_external_deqp