Add missing <vector> include in libdispatch_queue.hpp

[mikomikotaishi]

exec/libdispatch_queue.hpp uses std::vector (line 443 upstream, line 444 after my edits), but never includes <vector>. Although this typically arrives transitively through stdexec/execution.hpp, on libc++ 22, the include appears on C++23 but does not in C++26. stdexec/execution.hpp already includes the other std symbols used in this file transitively, but not std::vector.

#include <exec/libdispatch_queue.hpp>

int main() {
    return 0;
}

Result:

$ clang++ -std=c++2c -stdlib=libc++ -I include -fsyntax-only Test.cpp
exec/libdispatch_queue:443:12: error: no template named 'vector' in namespace 'std'

This, however, passes with -std=c++23.

This header only gets included on Apple platforms, and Linux/libstdc++ never compiles it. (I observed this on Homebrew LLVM clang 22.1.8 and bundled libc++, on macOS.)

The fix is simply adding #include <vector>.

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.