Now that `sincos` is a supported intrinsic in the LLVM dialect
(#160561) we are able to add the corresponding operation in 
the math dialect and add conversion patterns for LLVM and NVVM.

We have several benchmarks that use sine and cosine in hot-loops, and
saving some calculations by performing them together can benefit
performance. We would like to have a way to represent sincos in the math
dialect.

See https://github.com/llvm/llvm-project/pull/147168 for more info.

This patch adds the erfc op to the math dialect. It also does lowering
of the math.erfc op to libm calls. There is also a f32 polynomial
approximation for the function based on

https://stackoverflow.com/questions/35966695/vectorizable-implementation-of-complementary-error-function-erfcf
This is in turn based on
M. M. Shepherd and J. G. Laframboise, "Chebyshev Approximation of
(1+2x)exp(x^2)erfc x in 0 <= x < INF", Mathematics of Computation, Vol.
36, No. 153, January 1981, pp. 249-253.
The code has a ULP error less than 3, which was tested, and MLIR test
values were verified against the C implementation.

Introduce a subset of floating point classification ops to the Math
dialect. These ops mirror functions provided by the C math library and,
similarly to the existing `math.copysign`, belong to the math dialect.
Add a lowering of those ops to Nvidia libdevice calls when possible as
the first mechanism to exercise them.

Signed-Off By: Vivek Khandelwal <vivekkhandelwal1424@gmail.com>

Includes end-to-end tests for the cpu running, folders using `libm` and
lowerings to the corresponding `libm` operations.

Required for torch-mlir.
Cf. llvm/torch-mlir#2604 "Implement torch.aten.acos".

Return poison from foldBinary/unary if argument(s) is poison. Add ub dialect as dependency to affected dialects (arith, math, spirv, shape).
Add poison materialization to dialects. Add tests for some ops from each dialect.
Not all affected ops are covered as it will involve a huge copypaste.

Differential Revision: https://reviews.llvm.org/D159013