[physfs] Patches to fix behavior on macOS / Linux

[past-due]

Describe the pull request

Adds two patches to fix behavior (and runtime failure handling) on macOS / Linux / other POSIX-compatible.

• Handle EINTR (fixes runtime failures - more common on macOS Big Sur, and depending on system configuration and many other factors)
• Adds missing O_CLOEXEC / FD_CLOEXEC (recommended behavior for libraries)

All triplets should be supported.

I have reached out to upstream about these patches. Will update when there's a response.

[JackBoosY]

Can you report this to the upstream?

Thanks.

[past-due]

Can you report this to the upstream?

Thanks.

@JackBoosY:
I have reported this to the maintainer (no public link though, as unfortunately there doesn't appear to be a public bug-tracker so I had to message directly). Will post a comment here with updates whenever I hear back.

[ras0219-msft]

I'm uneasy about adding these code changes without some guidance from upstream -- I'm not familiar enough with the specific semantics and codebase to properly review it.

Assuming upstream gives the OK, then this LGTM

[JackBoosY]

Ping @past-due for response, does the upstream accept this changes?

[past-due]

Ping @past-due for response, does the upstream accept this changes?

Haven't heard back - I will ping them again.

[past-due]

@JackBoosY I'm pleased to note that upstream has now accepted these patches:

icculus/physfs@a9cb207
icculus/physfs@b8fa8fd

(They also recently moved to GitHub, which made this a bit easier.)