[libc][NFC] Ensure internal implementation is in __llvm_libc namespace

Summary: In preparation for D76818.

Reviewers: PaulkaToast, sivachandra, gchatelet

Reviewed By: PaulkaToast, sivachandra

Subscribers: MaskRay, tschuett, libc-commits

Differential Revision: https://reviews.llvm.org/D76967

libc/src/signal/linux/__restore.cpp

@@ -13,8 +13,12 @@
 #include "config/linux/syscall.h"
 #include "include/sys/syscall.h"
 
+namespace __llvm_libc {
+
 extern "C" void __restore_rt()
     __attribute__((no_sanitize("thread", "memory", "undefined", "fuzzer"),
                    hidden));
 
 extern "C" void __restore_rt() { __llvm_libc::syscall(SYS_rt_sigreturn); }
+
+} // namespace __llvm_libc

libc/src/string/memory_utils/memcpy_utils.h

@@ -20,14 +20,14 @@
 #define USE_BUILTIN_MEMCPY
 #endif
 
+namespace __llvm_libc {
+
 // This is useful for testing.
 #if defined(LLVM_LIBC_MEMCPY_MONITOR)
 extern "C" void LLVM_LIBC_MEMCPY_MONITOR(char *__restrict,
                                          const char *__restrict, size_t);
 #endif
 
-namespace __llvm_libc {
-
 // Copies `kBlockSize` bytes from `src` to `dst`.
 template <size_t kBlockSize>
 static void Copy(char *__restrict dst, const char *__restrict src) {

libc/src/threads/linux/thread_utils.h

@@ -14,6 +14,8 @@
 #include <stdatomic.h>
 #include <stdint.h>
 
+namespace __llvm_libc {
+
 // The futex data has to be exactly 4 bytes long. However, we use a uint type
 // here as we do not want to use `_Atomic uint32_t` as the _Atomic keyword which
 // is C only. The header stdatomic.h does not define an atomic type
@@ -35,4 +37,6 @@ struct ThreadParams {
   static constexpr uint32_t ClearTIDValue = 0xABCD1234;
 };
 
+} // namespace __llvm_libc
+
 #endif // LLVM_LIBC_SRC_THREADS_LINUX_THREAD_UTILS_H