ignore SIGPIPE in qemu-img and qemu-io

This prevents the tools from being stopped when they write data to a
closed connection in the other side.

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/qemu-img.c b/qemu-img.c
index dece1b3..b9a848d 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2322,6 +2322,10 @@
     const img_cmd_t *cmd;
     const char *cmdname;
 
+#ifdef CONFIG_POSIX
+    signal(SIGPIPE, SIG_IGN);
+#endif
+
     error_set_progname(argv[0]);
 
     qemu_init_main_loop();