Increase max for output image asserts to 32768

Increase max for output image asserts to 32768

In framework/qphelper/qpTestLog.c, two assertions assume that the
width and height of the output image are no larger than 16384. But
when testing in 1 x max FBO mode, and max FBO size is larger than
16384, these asserts would fire. This change relaxes the assertions
so they expect sizes up to 32768.

Author: Weiwan Liu <weiwliu@nvidia.com>

Components: Framework

VK-GL-CTS issue: 697

Affects: KHR-GL46.explicit_uniform_location.uniform-loc

Change-Id: If6c674a8728defba971851590b36ac1196c7a39d