[lldb] Get rid of HAVE_SIGACTION

[thakis]

Summary

The .cpp file uses SIGNAL_POLLING_UNSUPPORTED to guard the call
to sigaction, so use it in the .h file too. (LLVM also calls
sigaction without a guard on non-Windows.)

No behavior change.

[JDevlieghere]

LGTM

lldb/cmake/modules/LLDBGenerateConfig.cmake

 # This file contains all the logic for running configure-time checks
 
 include(CheckSymbolExists)
 include(CheckIncludeFile)
 include(CheckIncludeFiles)
 include(CheckLibraryExists)
 
 set(CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
 check_symbol_exists(ppoll poll.h HAVE_PPOLL)
 check_symbol_exists(ptsname_r stdlib.h HAVE_PTSNAME_R)
 set(CMAKE_REQUIRED_DEFINITIONS)
-check_symbol_exists(sigaction signal.h HAVE_SIGACTION)
 check_cxx_symbol_exists(accept4 "sys/socket.h" HAVE_ACCEPT4)
 
 check_include_file(termios.h HAVE_TERMIOS_H)
 check_include_file("sys/types.h" HAVE_SYS_TYPES_H)
 check_include_files("sys/types.h;sys/event.h" HAVE_SYS_EVENT_H)
 
 check_cxx_symbol_exists(process_vm_readv "sys/uio.h" HAVE_PROCESS_VM_READV)
 check_cxx_symbol_exists(__NR_process_vm_readv "sys/syscall.h" HAVE_NR_PROCESS_VM_READV)

lldb/include/lldb/Host/Config.h.cmake

 #cmakedefine01 HAVE_SYS_TYPES_H
 
 #cmakedefine01 HAVE_SYS_EVENT_H
 
 #cmakedefine01 HAVE_PPOLL
 
 #cmakedefine01 HAVE_PTSNAME_R
 
-#cmakedefine01 HAVE_SIGACTION
-
 #cmakedefine01 HAVE_PROCESS_VM_READV
 
 #cmakedefine01 HAVE_NR_PROCESS_VM_READV
 
 #ifndef HAVE_LIBCOMPRESSION
 #cmakedefine HAVE_LIBCOMPRESSION
 #endif
 

lldb/include/lldb/Host/MainLoop.h

 //===-- MainLoop.h ----------------------------------------------*- C++ -*-===//
 //
 // 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 LLDB_HOST_MAINLOOP_H
 #define LLDB_HOST_MAINLOOP_H
 
 #include "lldb/Host/Config.h"
 #include "lldb/Host/MainLoopBase.h"
 #include "llvm/ADT/DenseMap.h"
 #include <csignal>
 #include <list>
 
 #if !HAVE_PPOLL && !HAVE_SYS_EVENT_H && !defined(__ANDROID__)
 #define SIGNAL_POLLING_UNSUPPORTED 1
 #endif
private:
 
     friend class MainLoop;
     SignalHandle(const SignalHandle &) = delete;
     const SignalHandle &operator=(const SignalHandle &) = delete;
   };
 
   struct SignalInfo {
     std::list<Callback> callbacks;
-#if HAVE_SIGACTION
+#ifndef SIGNAL_POLLING_UNSUPPORTED
     struct sigaction old_action;
 #endif
     bool was_blocked : 1;
   };
   class RunImpl;
 
   llvm::DenseMap<IOObject::WaitableHandle, Callback> m_read_fds;
   llvm::DenseMap<int, SignalInfo> m_signals;