[roll] Roll fuchsia [roll] Roll llvm-project/libc [libc][math] Adding constexpr to tests for Double-type math functions  (#200681)

Similar to
```CPP
  constexpr uint64_t X_COUNT = 123;
  constexpr uint64_t X_START = FPBits(0.25).uintval();
  constexpr uint64_t X_STOP = FPBits(4.0).uintval();
  constexpr uint64_t X_STEP = (X_STOP - X_START) / X_COUNT;

  constexpr uint64_t Y_COUNT = 137;
  constexpr uint64_t Y_START = FPBits(0.25).uintval();
  constexpr uint64_t Y_STOP = FPBits(4.0).uintval();
  constexpr uint64_t Y_STEP = (Y_STOP - Y_START) / Y_COUNT;
  ```
  in [atan2_test.cpp](https://github.com/llvm/llvm-project/blob/main/libc/test/src/math/atan2_test.cpp)
  This PR tends to add constexpr to all double function tests-only

  Additonally, replacing
  ``` CPP
  LIBC_NAMESPACE::fputil::FPBits<double>(x).uintval();
   ```
to
```CPP
FPBits(x).uintval();
```
  Assisted using Copilot.

GitOrigin-RevId: 0f1f234990f40c942fb8b87cd2141c48848b8253
Original-Original-Revision: f3e496fe7ccad49173d1c1d6ebeb51d2b231087d

Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1634618
Original-Original-Revision: 307a22089c43017a344fa190a2d5f8d3517b0597
GitOrigin-RevId: 49180b53d30e8d0428663062927f8617998a8b65
Change-Id: I5ce4c42ea02735d190e763498fc3c9583a6b44e5
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1634910
Cr-Commit-Position: refs/heads/main@{#193830}