sigpipe: if mbedTLS is used, ignore SIGPIPE

mbedTLS doesn't have a sigpipe management. If a write/read occurs when
the remote closes the socket, the signal is raised and kills the
application.  Use the curl mecanisms fix this behavior.

Signed-off-by: Jeremie Rapin <j.rapin@overkiz.com>

Closes #3502

lib/sigpipe.h

@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -23,7 +23,8 @@
  ***************************************************************************/
 #include "curl_setup.h"
 
-#if defined(HAVE_SIGNAL_H) && defined(HAVE_SIGACTION) && defined(USE_OPENSSL)
+#if defined(HAVE_SIGNAL_H) && defined(HAVE_SIGACTION) &&        \
+  (defined(USE_OPENSSL) || defined(USE_MBEDTLS))
 #include <signal.h>
 
 struct sigpipe_ignore {