Make ccompat.h less retard.

[ghost]

<alloca.h> is Linux-specific header. Also <stdlib.h> may be used instead of <alloca.h> on Linux, so basically it is a useless header.

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This change is 

[CLAassistant]

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[ghost]

@CLAassistant who the fuck are those many open source projects? Fuck your licenses.

[ghost]

@iphydf what have you done? FreeBSD is not the only OS which doesn't have <alloca.h>

[iphydf]

What I observed: someone opens a PR talking about "retarded" headers, then that someone starts swearing at a bot and deletes the repository fork this PR was made from.

This makes me think that someone is clearly no longer interested in contributing, so I'll helpfully close the PR. If I was wrong, I am happy to chat about any technical or organisational issues you see and would like to fix.

[ghost]

@iphydf removing fork doesn't prevent from merging changes, I simply don't need the copy of this repository, that's why I always remove local copy after creating retard PR

[iphydf]

Ok, can you reopen the PR then?

[ghost]

@iphydf oh, I see the change is too hard to reproduce. I'll just store the diff locally.