[te] Fix clamp with uint8 args (#49143)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49143
Riddle me this, batman: how could `torch.clamp(torch.tensor([0], dtype=torch.uint8), -10, 10)` equal `10`? The answer: the min/max args are first cast to the dtype of the input, giving min=246 and max 10. Then you have to apply Min and Max in the right order: `Min(Max(in, min), max)`. Differ in any way and you're doomed. Hooray.
This PR makes TE match eager mode for this operator, plus fixes a major facepalm in the llvm min/max codegen where we were always generating signed comparisons.
ghstack-source-id: 118415318
Test Plan: `buck test //caffe2/test:{jit,tensorexpr}`
Reviewed By: robieta
Differential Revision: D25456366
fbshipit-source-id: dde3c26c2134bdbe803227601fa3d23eaac750fb
