[libc] implement wmemcmp

[michaelrj-google]

Described in C23 (page 454): https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3220.pdf#page=454

wmemcmp compares the first n wide chars.

Here's a checklist for what you'll need to do for this:

• Add the implementation of wmemcmp in /src/wchar
• Add tests for wmemcmp in /test/src/wchar
• Add wmemcmp to entrypoints.txt for at least x86_64 and whatever you're building on
• Add wmemcmp to include/wchar.yaml

(Reserved for specific assignee)

[llvmbot]

@llvm/issue-subscribers-libc

Author: Michael Jones (michaelrj-google)

Described in C23 (page 454): https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3220.pdf#page=454

wmemcmp compares the first n wide chars.

Here's a checklist for what you'll need to do for this:

• Add the implementation of wmemcmp in /src/wchar
• Add tests for wmemcmp in /test/src/wchar
• Add wmemcmp to entrypoints.txt for at least x86_64 and whatever you're building on
• Add wmemcmp to include/wchar.yaml

(Reserved for specific assignee)

[sribee8]

I can work on this!