This trivial diff gets rid of noisy warnings such as
```
./src/common/ignore.c:274:13: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
274 | ignore_load ()
| ^
| void
```
when building with modern clang. This is cosmetic since these functions
are actually prototyped in a header, so if the header is in scope it's
not possible to call them with an arbitrary number of arguments.
