Building lib/ubsan.c with gcc-9 results in a ton of nasty warnings like
this one:
lib/ubsan.c warning: conflicting types for built-in function
‘__ubsan_handle_negate_overflow’; expected ‘void(void *, void *)’ [-Wbuiltin-declaration-mismatch]
The kernel's declarations of __ubsan_handle_*() often uses 'unsigned
long' types in parameters while GCC these parameters as 'void *' types,
hence the mismatch.
Fix this by using 'void *' to match GCC's declarations.