several fixes and improvments

- set errno to 0 if it is checked right after a libc call
  - ignore SIGPIPE as we want to avoid signal handling where possible
  - fixed another issue in nDPIsrvd/c-json-stdout which caused buffering errors

Signed-off-by: Toni Uhlig <matzeton@googlemail.com>

examples/c-json-stdout/c-json-stdout.c

@@ -61,7 +61,7 @@ int main(void)
         }
 
         buf_used += bytes_read;
-        while (json_bytes == 0 && buf_used >= nDPIsrvd_JSON_BYTES + 1)
+        while (buf_used >= nDPIsrvd_JSON_BYTES + 1)
         {
             if (buf[nDPIsrvd_JSON_BYTES] != '{')
             {