vcxproj: also link-or-copy builtins

The default location for `.exe` files linked by Visual Studio depends on
the mode (debug vs release) and the architecture. Meaning: after a full
build, there is a `git.exe` in the top-level directory, but none of the
built-ins are linked..

When running a test script in Git Bash, it therefore would pick up the
wrong, say, `git-receive-pack.exe`: the one installed at the same time
as the Git Bash.

Absolutely not what we want. We want to have confidence that our test
covers the MSVC-built Git executables, and not some random stuff.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/buildsystems/Generators/Vcxproj.pm

@@ -274,6 +274,9 @@ EOM
   </Target>
 EOM
     }
+    if ($target eq 'git') {
+      print F "  <Import Project=\"LinkOrCopyBuiltins.targets\" />\n";
+    }
     print F << "EOM";
 </Project>
 EOM