Fix build errors on older versions of gcc

[omjavaid]

Summary

This patch fixes some build errors while building with gcc 4.7.x or below.

Errors occured while building with arm-linux-gnueabi-gcc which is still using gcc 4.6 release.

[tberghammer]

Looks good to me, but I am not sure if gcc-4.6 supports all c++11 feature we are using and LLVM officially supports gcc-4.7+, so you might run into other issues also using gcc-4.6. If possible, I suggest to try to upgrade your compiler to avoid further issues.

[clayborg]

As long as there are no other changes and LLDB actually does build and run using a gcc 4.6 built binary, go ahead and check this in. If anything still fails and gcc 4.6 can compile everything leave it out.

source/Host/common/Host.cpp

~ScopedPThreadCancelDisabler()
             ::pthread_setcancelstate (m_old_state, 0);
     }
 private:
     int m_old_state;    // Save the old cancelability state.
 };
 #endif // __linux__
 
 #ifdef __linux__
+#if defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8))
+static __thread volatile sig_atomic_t g_usr1_called;
+#else
 static thread_local volatile sig_atomic_t g_usr1_called;
+#endif
 
 static void
 SigUsr1Handler (int)
 {
     g_usr1_called = 1;
 }
 #endif // __linux__
 

source/Host/posix/PipePosix.cpp

 //===-- PipePosix.cpp -------------------------------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Host/posix/PipePosix.h"
 #include "lldb/Host/FileSystem.h"
 #include "lldb/Host/HostInfo.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/FileSystem.h"
 
+#if defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8))
+#define _GLIBCXX_USE_NANOSLEEP
+#endif
+
 #include <functional>
 #include <thread>
 
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <unistd.h>
 #include <sys/types.h>

source/Plugins/Process/Linux/NativeProcessLinux.h

private:
             char const **m_envp;               // Process environment.
             const FileSpec m_stdin_file_spec;  // Redirect stdin if not empty.
             const FileSpec m_stdout_file_spec; // Redirect stdout if not empty.
             const FileSpec m_stderr_file_spec; // Redirect stderr if not empty.
             const FileSpec m_working_dir;      // Working directory or empty.
             const ProcessLaunchInfo &m_launch_info;
         };
 
-        typedef std::function<::pid_t(Error &)> InitialOperation;
+        typedef std::function< ::pid_t(Error &)> InitialOperation;
 
         // ---------------------------------------------------------------------
         // Private Instance Methods
         // ---------------------------------------------------------------------
         NativeProcessLinux ();
 
         /// Launches an inferior process ready for debugging.  Forms the
         /// implementation of Process::DoLaunch.

source/Plugins/Process/Linux/NativeThreadLinux.cpp

 
 #include "llvm/ADT/SmallString.h"
 
 #include "Plugins/Process/POSIX/CrashReason.h"
 
 #include <sys/syscall.h>
 // Try to define a macro to encapsulate the tgkill syscall
 #define tgkill(pid, tid, sig) \
-    syscall(SYS_tgkill, static_cast<::pid_t>(pid), static_cast<::pid_t>(tid), sig)
+    syscall(SYS_tgkill, static_cast< ::pid_t>(pid), static_cast< ::pid_t>(tid), sig)
 
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::process_linux;
 
 namespace
 {
     void LogThreadStopInfo (Log &log, const ThreadStopInfo &stop_info, const char *const header)