cmUVSignalHackRAII: Drop outdated and unused libuv SA_RESTART workaround

It is only needed for libuv < 1.19, but since commit c050d6a01e
(string(TIMESTAMP): add %f specifier for microseconds, 2022-01-27,
v3.23.0-rc1~59^2) we require libuv >= 1.28.

Source/CMakeLists.txt

@@ -450,7 +450,6 @@ add_library(
   cmUVProcessChain.h
   cmUVStream.h
   cmUVStreambuf.h
-  cmUVSignalHackRAII.h
   cmVariableWatch.cxx
   cmVariableWatch.h
   cmVersion.cxx

Source/CTest/cmCTestMultiProcessHandler.cxx

@@ -40,7 +40,6 @@
 #include "cmRange.h"
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
-#include "cmUVSignalHackRAII.h" // IWYU pragma: keep
 #include "cmWorkingDirectory.h"
 
 namespace cmsys {
@@ -132,9 +131,6 @@ void cmCTestMultiProcessHandler::RunTests()
   if (this->HasCycles || this->HasInvalidGeneratedResourceSpec) {
     return;
   }
-#ifdef CMAKE_UV_SIGNAL_HACK
-  cmUVSignalHackRAII hackRAII;
-#endif
   this->TestHandler->SetMaxIndex(this->FindMaxIndex());
 
   uv_loop_init(&this->Loop);

Source/cmUVSignalHackRAII.h

@@ -1,45 +0,0 @@
-/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
-   file Copyright.txt or https://cmake.org/licensing for details.  */
-#pragma once
-#include "cmConfigure.h" // IWYU pragma: keep
-
-#include <cm3p/uv.h>
-
-#if defined(CMAKE_USE_SYSTEM_LIBUV) && !defined(_WIN32) &&                    \
-  UV_VERSION_MAJOR == 1 && UV_VERSION_MINOR < 19
-#  define CMAKE_UV_SIGNAL_HACK
-#  include "cmUVHandlePtr.h"
-/*
-   libuv does not use SA_RESTART on its signal handler, but C++ streams
-   depend on it for reliable i/o operations.  This RAII helper convinces
-   libuv to install its handler, and then revises the handler to add the
-   SA_RESTART flag.  We use a distinct uv loop that never runs to avoid
-   ever really getting a callback.  libuv may fill the hack loop's signal
-   pipe and then stop writing, but that won't break any real loops.
- */
-class cmUVSignalHackRAII
-{
-  uv_loop_t HackLoop;
-  cm::uv_signal_ptr HackSignal;
-  static void HackCB(uv_signal_t*, int) {}
-
-public:
-  cmUVSignalHackRAII()
-  {
-    uv_loop_init(&this->HackLoop);
-    this->HackSignal.init(this->HackLoop);
-    this->HackSignal.start(HackCB, SIGCHLD);
-    struct sigaction hack_sa;
-    sigaction(SIGCHLD, nullptr, &hack_sa);
-    if (!(hack_sa.sa_flags & SA_RESTART)) {
-      hack_sa.sa_flags |= SA_RESTART;
-      sigaction(SIGCHLD, &hack_sa, nullptr);
-    }
-  }
-  ~cmUVSignalHackRAII()
-  {
-    this->HackSignal.stop();
-    uv_loop_close(&this->HackLoop);
-  }
-};
-#endif

Source/cmWorkerPool.cxx

@@ -18,7 +18,6 @@
 #include "cmRange.h"
 #include "cmStringAlgorithms.h"
 #include "cmUVHandlePtr.h"
-#include "cmUVSignalHackRAII.h" // IWYU pragma: keep
 
 /**
  * @brief libuv pipe buffer class
@@ -516,9 +515,6 @@ public:
   static void UVSlotEnd(uv_async_t* handle);
 
   // -- UV loop
-#ifdef CMAKE_UV_SIGNAL_HACK
-  std::unique_ptr<cmUVSignalHackRAII> UVHackRAII;
-#endif
   std::unique_ptr<uv_loop_t> UVLoop;
   cm::uv_async_ptr UVRequestBegin;
   cm::uv_async_ptr UVRequestEnd;
@@ -563,9 +559,6 @@ cmWorkerPoolInternal::cmWorkerPoolInternal(cmWorkerPool* pool)
 {
   // Initialize libuv loop
   uv_disable_stdio_inheritance();
-#ifdef CMAKE_UV_SIGNAL_HACK
-  UVHackRAII = cm::make_unique<cmUVSignalHackRAII>();
-#endif
   this->UVLoop = cm::make_unique<uv_loop_t>();
   uv_loop_init(this->UVLoop.get());
 }