Even if using `%f` the `printf_float` module was not used.
When running the test on `samr21-xpro` and `arduino-mega2560` the float
is not printed correctly.
* samr21-xpro ` false positive rate.`
* arduino-mega2560 `? false positive rate.`
As the arduino-mega2560 does not handle printf_float use
`fmt/print_float`.
The output should be flushed before using fmt/print functions if
available as they do not use `printf` buffer.
`bloom_t` is defined as a struct.
`_t` can mislead the user to think of bloom_t
as a typedef (see our coding conventions) instead of a struct.
Thus, I modified `struct bloom_t` to be a *typedefed* struct.
Another solution would be to rename bloom_t to sth. like bloom_s
everywhere and use `struct bloom_s` instead of `bloom_t`.
