[compiler-rt] [libc] [libc][sched] Implement proxy headers for `cpu_set_t`, `struct sched_param` and `sched_macros`. (PR #126303)

[Krishna Pandey via llvm-commits]

================
@@ -0,0 +1,27 @@
+//===-- Definition of macros from sched.h ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_HDR_SCHED_MACROS_H
+#define LLVM_LIBC_HDR_SCHED_MACROS_H
+
+#ifdef LIBC_FULL_BUILD
+
+#ifndef _SCHED_H
----------------
krishna2803 wrote:

guess i'll just have to work on this using the github workflow failures only lol. I tried:

```
cmake -S ../runtimes -GNinja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_RUNTIMES=libc -DLLVM_USE_LINKER=lld LLVM_TARGETS_TO_BUILD=X86 -DLLVM_ENABLE_RUNTIMES="libc;compiler-rt" -DCOMPILER_RT_SCUDO_STANDALONE_BUILD_SHARED=OFF -DCOMPILER_RT_BUILD_GWP_ASAN=OFF -DLLVM_LIBC_INCLUDE_SCUDO=ON -DCOMPILER_RT_BUILD_SCUDO_STANDALONE_WITH_LLVM_LIBC=ON -DLLVM_LIBC_FULL_BUILD=ON
```
followed by:
```
ninja check-libc
```

and i'm not able to reproduce these errors (on X86) so these are specific to aarch64 and i have no other way of testing for that architecture.

https://github.com/llvm/llvm-project/pull/126303