Aplies a patch to Qt that fixes the non-determinism by modifying Qt. The
source of the non-determinism is how LLVM 8 optimizes qt_intersect_spans
when compiling. The particular optimization that seems to be causing the
problems is that a temp variable is being added for spans->y. For some
reason, when it does this, it chooses different instructions to use when
making that variable. We bypass this problem by patching
qt_intersect_spans to always make and use this local variable.
Github-Pull: #20447
Rebased-From: 8f7d1b39efbe65ab2747c593cc3560d4a449a333
Tree-SHA512: 558da5c2bb0373e2a89f2c219170f802036e0e87cc8e808336b23d074152cb893007a440f46ec957156b0921355cd18502710f2d224f27bc26e934c50ebebc41
ab23a83400