Signal polling is supported with pselect (re-land r313704 without a Windows breakage)

Older Android API levels don't have ppoll, but LLDB works just fine,
since on Android it always uses pselect anyway.

llvm-svn: 313726

lldb/include/lldb/Host/MainLoop.h

@@ -15,7 +15,11 @@
 #include "llvm/ADT/DenseMap.h"
 #include <csignal>
 
-#if !HAVE_PPOLL && !HAVE_SYS_EVENT_H
+#ifdef __ANDROID__
+#define FORCE_PSELECT
+#endif
+
+#if !HAVE_PPOLL && !HAVE_SYS_EVENT_H && !defined(FORCE_PSELECT)
 #define SIGNAL_POLLING_UNSUPPORTED 1
 #endif
 

lldb/source/Host/common/MainLoop.cpp

@@ -38,10 +38,6 @@
 #define POLL poll
 #endif
 
-#ifdef __ANDROID__
-#define FORCE_PSELECT
-#endif
-
 #if SIGNAL_POLLING_UNSUPPORTED
 #ifdef LLVM_ON_WIN32
 typedef int sigset_t;