mobical.cpp: define MAP_ANONYMOUS if undefined

[barracuda156]

Trivial fix for platforms where MAP_ANONYMOUS is not present.

[m-fleury]

Seems to be such an macOS specific thing that even apple provides that ifdef in some places https://github.com/apple/darwin-xnu/blob/0a798f6738bc1db01281fc08ae024145e84df927/bsd/sys/mman.h#L127

[m-fleury]

1. Can you change your code to:

#ifdef __APPLE__

instead of testing if MAP_ANONYMOUS is defined (this makes it more clear when the variable is not defined).

2. Can you sign your commit as described in the CONTRIBUTING.md document?

[barracuda156]

@m-fleury This is not really specific to macOS, I think, though a number of macOS versions are affected (everything before 10.11).
Linux seems to recognize either: https://man7.org/linux/man-pages/man2/mmap.2.html (so at least MAP_ANON is not Apple-only).

Maybe adopt the version from Ruby upstream?
ruby/ruby@c0251c6

[m-fleury]

Right according to this issue, the situation is a mess and we do indeed need both (even though I have no idea CaDiCaL works on any of the machines where only MAP_ANONYMOUS is defined).

Thanks for the report!