Fix RHEL 6 build with missing cerrno and some other Include What You Use warnings.

Differential revision: https://reviews.llvm.org/D26171

llvm-svn: 285710

lldb/source/Host/posix/MainLoopPosix.cpp

@@ -8,10 +8,13 @@
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Host/posix/MainLoopPosix.h"
-
-#include <vector>
-
 #include "lldb/Core/Error.h"
+#include <algorithm>
+#include <cassert>
+#include <cerrno>
+#include <csignal>
+#include <vector>
+#include <sys/select.h>
 
 using namespace lldb;
 using namespace lldb_private;