[lldb] Remove some nanosleep preprocessor magic

It's obsolete, as we use (portable) std::this_thread::sleep_for now.

GitOrigin-RevId: 1db2888e70709930da6c22ab83706c7695962ace
diff --git a/source/Host/posix/PipePosix.cpp b/source/Host/posix/PipePosix.cpp
index 7cd05a1..2ccf000 100644
--- a/source/Host/posix/PipePosix.cpp
+++ b/source/Host/posix/PipePosix.cpp
@@ -12,13 +12,6 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Errno.h"
 #include "llvm/Support/FileSystem.h"
-
-#if defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8))
-#ifndef _GLIBCXX_USE_NANOSLEEP
-#define _GLIBCXX_USE_NANOSLEEP
-#endif
-#endif
-
 #include <functional>
 #include <thread>