[winpcap] build error on x64-windows

Package: winpcap:x64-windows@4.1.3#12

**Host Environment**

- Host: x64-windows
- Compiler: MSVC 19.44.35225.0
- CMake Version: 4.2.3
- vcpkg-tool version: 2026-04-08-e0612b42ce44e55a0e630f2ee9d3c533a63d8bc1
vcpkg-scripts version: d13fa75214 2026-04-14 (5 hours ago)

**To Reproduce**

`vcpkg install winpcap`

**Failure logs**

```
Downloading https://www.winpcap.org/install/bin/WpcapSrc_4_1_3.zip -> WpcapSrc_4_1_3.zip
Successfully downloaded WpcapSrc_4_1_3.zip
-- Extracting source C:/tools/vcpkg/downloads/WpcapSrc_4_1_3.zip
-- Applying patch C:/tools/vcpkg/buildtrees/winpcap/src/packetNtx.patch
-- Applying patch C:/tools/vcpkg/buildtrees/winpcap/src/wpcap.patch
-- Applying patch bison-flex.patch
-- Using source at C:/tools/vcpkg/buildtrees/winpcap/src/4_1_3-12e43b82d9.clean
Downloading https://github.com/lexxmark/winflexbison/releases/download/v2.5.24/win_flex_bison-2.5.24.zip -> win_flex_bison-2.5.24.zip
Successfully downloaded win_flex_bison-2.5.24.zip
CMake Error at scripts/cmake/vcpkg_execute_required_process.cmake:127 (message):
Command failed: devenv.exe Packet.sln /Upgrade
Working Directory: C:/tools/vcpkg/buildtrees/winpcap/src/4_1_3-12e43b82d9.clean/packetNtx/Dll/Project
Error code: no such file or directory
See logs for more information:

Call Stack (most recent call first):
ports/winpcap/portfile.cmake:59 (vcpkg_execute_required_process)
scripts/ports.cmake:206 (include)

```

Start with ports/winpcap/portfile.cmake at line 59 and reproduce the failure with `vcpkg install winpcap` on x64-windows. Inspect the `devenv.exe Packet.sln /Upgrade` invocation and the accompanying build logs. Done means the winpcap port builds successfully in the reported environment.

Written by the indexing model from the issue text.