docs: the verification found the packaged toolset could not link a default build

[Sunrisepeak]

Summary

Not a planned item — it turned up while working through the "not covered" list in the cross-repo plan, checking whether the packaged 14.52 toolset could build xrgui. It could not, and neither could it build anything else.

The payload set carried only the static CRT (libcmt / libcpmt / libvcruntime), so /MD — the default — failed on an unresolved msvcprt.lib. The header decides:

#if defined(_DLL) && !defined(_STATIC_CPPLIB)
#define _LIB_STEM "msvcprt"      // /MD  <- absent
#else
#define _LIB_STEM "libcpmt"      // /MT  <- present

Fixed in openxlings/xim-pkgindex#630 (the libs live in Microsoft.VC.<ver>.CRT.x64.Store.base — a name that reads as UWP, which is why it was skipped).

Why it belongs in this doc

Because of what it says about the acceptance table in §4. Both of these were true at the same time as the toolchain being unusable:

• 1790 static checks pass
• windows-test installs it on a real Windows runner, green

installed() checked cl.exe and std.ixx — both present — and nothing anywhere links with this toolset, so no gate could have reported it.

An "installed" criterion weaker than "usable" reports that the archive unpacked, not that the package works.

The "not covered" section is renumbered and gains the honest version of this: strengthening installed() makes file presence stricter, which is not the same as links successfully. Only xrgui's V3 covers that, and it has not run yet.

Test plan

• Docs only, no runtime change
• The use_ansi.h quote is from the 14.52 CRT.Headers.base payload, extracted locally