C doesn't require that int* and void* have the same representation. On some (very) old machines, loads and stores worked only at the granularity of a machine word (typically 16 bits, though sometimes larger). An int* on such a machine was represented as a (word) address, but a char* might be a pair of an address and a byte offset. Accessing a char required a load an a shift or mask.

I think binutils still supports at least one such architecture (though FreeBSD doesn't).

Generally, I think we lower WARNS on contrib code, especially poor-quality GNU code, though when the fix is this simple it might be worth retaining - especially as binutils is due a de-orbit burn soon and is unlikely to ever receive an update..