Fix fifo length (issue #66)

Jan Breuer

2016-02-14 fbd16b32739a35ed3d3cf7e9aa4cfb6a75758e46

 libscpi/inc/scpi/types.h

@@ -204,6 +204,7 @@
    struct _scpi_fifo_t {
        int16_t wr;
        int16_t rd;
        int16_t count;
        int16_t size;
        int16_t * data;
    };