* Clean up some pointless code

* Improve comment on Halide::round

* Make Halide::round round to even as documented

* Explicitly set the rounding mode in the C backend

* Use rint on ptx, which is documented to round to even

* round to even on win32

* the nvidia libdevice is buggy for doubles

See https://reviews.llvm.org/D85236

* Add missing include to C output

* Fix rounding in opencl

* Don't test opencl with doubles if CLDoubles is not enabled

* Work around hexagon issue

* Don't try to emit roundeven on wasm

* wasm doesn't support float16

* Add vectorizable lowering for round on platforms without roundeven

* Use rint on metal for Halide::round

* Make round an intrinsic

* Constant-fold round in simplifier

* d3d12 fix

* Bounds of Call::round

* Teach the mullapudi cost model about round

* Handle PureIntrinsics of const args in bounds

* scatter, undef, and require aren't pure

* metal doesn't support doubles

* More parens

* Add missing return

* Add vector versions of rint for wasm

* Use nearbyint for wasm instead of rint

* revert change to mangling

* d3d12 doesn't like double input/output buffers

* Lower round on arm-32 not-linux

* Don't simplify lowering of round-to-nearest-ties-to-even in codegen

* Fix infinite loop in round lowering on arm-32-notlinux

* Take care to never revisit args in bounds call visitor

* Remove defunct comment

Co-authored-by: Steven Johnson <srj@google.com>