Make alloca() API both GNU and Microsoft compatible
I've attached a proposed implementation patch, against wsl-5.1, which should meet the objective. In the absence of significant objection, (say nett negative votes equivalent to 70% or more of mingw-users list subscribers), I will incorporate this for WSL-5.1.1
The changes required, to implement the <alloca.h> API, are now in the git repository, and will be incorporated into the upcoming wsl-5.2 release.
The further suggested <malloc.h> changes relate, primarily, to improved (legacy) support for Microsoft's _aligned_malloc() (and complementary) API; this may be best addressed under ticket #38607.
As suggested in this mailing list discussion thread, (and this message in particular), please consider adapting the existing alloca() implementation in <malloc.h>, to make it equally accessible via a new <alloca.h> header, and so offer added conformance with the corresponding GNU implementation.
In the process, please also update the existing <malloc.h> implementation of other included APIs, to make them compatible with current Windows technologies.