Ignore SIGPIPE on all platforms emitting it.

* Boost ASIO should do it but unfortunately it seems it does not on OS X and Linux.
  See http://www.boost.org/doc/libs/1_55_0/boost/asio/io_service.hpp
  and http://stackoverflow.com/a/12387971/388803.
* This prevents being killed in the OPI when
  the process can not write to its Tk window anymore.
  (It is also unreasonable to kill the whole process in a multi-VM world)

vm/boostenv/main/boostenv.hh

@@ -25,6 +25,7 @@
 #ifndef MOZART_BOOSTENV_H
 #define MOZART_BOOSTENV_H
 
+#include <csignal>
 #include <exception>
 #include <fstream>
 
@@ -114,6 +115,11 @@ BoostEnvironment::BoostEnvironment(const VMStarter& vmStarter) :
   vmStarter(vmStarter) {
   // Set up a default boot loader
   setBootLoader(&defaultBootLoader);
+
+  // Ignore SIGPIPE ourselves since Boost does not always do it
+#ifdef SIGPIPE
+  std::signal(SIGPIPE, SIG_IGN);
+#endif
 }
 
 VMIdentifier BoostEnvironment::addVM(const std::string& app, bool isURL,