This PR adds benchmarking for `atan2()`, `__nv_atan2()`, and
`__ocml_atan2_f64()` using the same setup as `sin()`. This PR also adds
support for throughout bencmarking for functions with 2 inputs.

This PR adds benchmarking for `sinf()` using the same set up as `sin()`
but with a smaller range for floats.

Previously, `AmdgpuSinTwoPow_128` and others were too large for their
table cells. This PR shortens the name to `AmdSin...`

There were also some `-` missing in the separator. This PR instead
creates the separator string using the length of the headers.

This PR implements
https://github.com/lntue/llvm-project/commit/2a158426d4b90ffaa3eaecc9bc10e5aed11f1bcf
to provide better throughput benchmarking for libc `sin()` and
`__nv_sin()`.

These changes have not been tested on AMDGPU yet, only compiled.

This PR adds support for benchmarking `__ocml_sin_f64()` against
`sin()`. This PR is currently a draft because I do not have access to an
AMD GPU and was not able to test the PR, but the code compiled when I
ran `ninja gpu-benchmark` from `runtimes-amdgcn-amd-amdhsa-bins`

Co-authored-by: Joseph Huber <huberjn@outlook.com>

This PR adds sin benchmarking for a range of values and on a
pregenerated random distribution.

This PR runs benchmarks on a 32 threads (A single warp on NVPTX) by
default, adding the option for single threaded benchmarks. We can
specify that a benchmark should be run on a single thread using the
`SINGLE_THREADED_BENCHMARK()` macro.

I chose to use a flag here so that other options could be added in the
future.

There was previously an issue where registering multiple benchmarks in
the same file would only give the results for the last benchmark to run.
This PR fixes the issue.

@jhuber6

PR for adding microbenchmarking infrastructure for NVPTX. `nvlink`
cannot perform LTO, so we cannot inline `libc` functions and this
function call overhead is not adjusted for during microbenchmarking.