Increase minimum C standard from C89/C90 to C11 about zstd

[Cyan4973]

A compression standard is only useful if one can expect it to be supported by the receiver side. As a consequence, the promise that the Zstandard reference library can be compiled on any platform, and therefore the Zstandard format can be decoded on any platform, is a fairly important one for the health of the ecosystem.
Therefore, we still intend to preserve C90 compatibility of the code base for the foreseeable future.

[gruenich]

Do you have any data that C90 coveres considerably more platforms compared to C11? The Kernel's move went without noticeable fallout. I thought it could be considered for Zstd 1.6, 1.7, or even 2.0.

I understand your position, feel free to close this issue as won't fix.

[Cyan4973]

2.0 possibly,
but not in the foreseeable future.