*: `frr-format` with unmodified GCC

*: `frr-format` with unmodified GCC

Since there's very few locations where the `frr-format` actually prints
false positive warnings, consensus seems to be to just work around the
false positives even if the code is correct.

In fact, there is only one pattern of false positives currently, in
`bfdd/dplane.c` which does `vty_out("%"PRIu64, (uint64_t)be64toh(...))`.
The workaround/fix for this is a replacement `be64toh` whose type is
always `uint64_t` regardless of what OS we're on, making the cast
unnecessary.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>