[vcpkg] proper errorcheck during files installation

[Maximus5]

If during install_files_and_write_listfile an error happens in for (auto&& file : files) loop, every file in files is skipped due to "saved" error, even if fs.symlink_status(file, ec) succeeds.

This PR fixes the behavior, correct files aren't skipped.

Sample output of vcpkg install libressl[tools]:x64-windows

without fix - vcpkg complains every file after an error occurs

Building package libressl[core,tools]:x64-windows... done
Installing package libressl[core,tools]:x64-windows...
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\installed\x64-windows\debug\lib\crypto.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\packages\libressl_x64-windows\debug\lib\ssl-47.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\packages\libressl_x64-windows\debug\lib\ssl.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\packages\libressl_x64-windows\debug\lib\tls-19.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\packages\libressl_x64-windows\debug\lib\tls.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\packages\libressl_x64-windows\etc: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\packages\libressl_x64-windows\etc\ssl: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\packages\libressl_x64-windows\etc\ssl\cert.pem: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\packages\libressl_x64-windows\etc\ssl\openssl.cnf: A required privilege is not held by the client.
...
   and about 100 wrong files
...
Installing package libressl[core,tools]:x64-windows... done

with fix - only proper errors

Building package libressl[core,tools]:x64-windows... done
Installing package libressl[core,tools]:x64-windows...
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\installed\x64-windows\debug\lib\crypto.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\installed\x64-windows\debug\lib\ssl.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\installed\x64-windows\debug\lib\tls.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\installed\x64-windows\lib\crypto.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\installed\x64-windows\lib\ssl.lib: A required privilege is not held by the client.
failed: C:\SRC\vcpkg\toolsrc\msbuild.x64.debug\installed\x64-windows\lib\tls.lib: A required privilege is not held by the client.
Installing package libressl[core,tools]:x64-windows... done

[ras0219]

I believe that this should actually be moved into Files::<anonymous>::status_implementation(). The contract for APIs accepting error_code& is that they will clear the error code during a success path, therefore this is a bug in fs.symlink_status() (which transitively calls the above function).

[Maximus5]

Moved, works for me

[ras0219-msft]

Thanks for the fix!