Reapply "[compiler-rt][XRay] Make xray_interface.h C compliant" (#141728)

Changes to initial PR (#140068):

- Mark failing test as unsupported for powerpc64le, as test failure is
unrelated to PR changes. See
https://github.com/llvm/llvm-project/issues/141598

---

Original description (from #140068)

The XRay interface header uses no C++ specific features aside from using
the std namespace and including the C++ variant of C headers. Yet, these
changes prevent using `xray_interface.h` in external tools relying on C
for different reasons. Make this header C compliant by using C headers,
removing the std namespace from std::size_t and guard `extern "C"`.

To make sure that further changes to not break the interface
accidentially, port one test from C++ to C. This requires the C23
standard to officially support the attribute syntax used in this test
case.

Note that this only resolves this issue for `xray_interface.h`.
`xray_records.h` is also not C compliant, but requires more work to
port.

Fixes #139902

Signed-off-by: Jan André Reuter <j.reuter@fz-juelich.de>

0 files changed, 0 insertions, 0 deletions