Steve Lhomme authored Mar 02, 2022 and Hugo Beauzée-Luyssen committed Mar 03, 2022

ssize_t is not a standard C type. In some cases it's supposed to hold no more
than a long [1]. That's 2 GB in normal case which is enough for 16k*16k 16-bit
RGBA.

> The implementation shall support one or more programming environments in
> which the widths of blksize_t, pid_t, size_t, ssize_t, and suseconds_t are no
> greater than the width of type long. The names of these programming
> environments can be obtained using the confstr() function or the getconf
> utility.

Make sure the new type is equivalent to the old one so we don't break ABI.
And a recompilation will hopefully no bring any warning (otherwise that was
assumed to be ssize_t by the host app was not correct).

[1] https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_types.h.html