Fix windows build after r329296

Add a couple of #include <csignal>s.

llvm-svn: 329309
diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index a3b6d12..9d49cfa 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -24,6 +24,7 @@
 
 // C++ Includes
 #include <algorithm>
+#include <csignal>
 #include <map>
 #include <mutex>
 #include <sstream>