ci(vs-build): stop passing the iconv library location explicitly

Something changed in `vcpkg` (which we use in our Visual C++ build to
provide the dependencies such as libcurl) and our `vs-build` job started
failing in CI. The reason is that we had a work-around in place to help
CMake find iconv, and this work-around is neither needed nor does it
work anymore.

For the full discussion with the vcpkg project, see this comment:
https://github.com/microsoft/vcpkg/issues/14780#issuecomment-735368280

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

.github/workflows/main.yml

@@ -201,7 +201,6 @@ jobs:
       shell: bash
       run: |
         cmake `pwd`/contrib/buildsystems/ -DCMAKE_PREFIX_PATH=`pwd`/compat/vcbuild/vcpkg/installed/x64-windows \
-        -DIconv_LIBRARY=`pwd`/compat/vcbuild/vcpkg/installed/x64-windows/lib/libiconv.lib -DIconv_INCLUDE_DIR=`pwd`/compat/vcbuild/vcpkg/installed/x64-windows/include \
         -DMSGFMT_EXE=`pwd`/git-sdk-64-minimal/mingw64/bin/msgfmt.exe -DPERL_TESTS=OFF -DPYTHON_TESTS=OFF -DCURL_NO_CURL_CMAKE=ON
     - name: MSBuild
       run: msbuild git.sln -property:Configuration=Release -property:Platform=x64 -maxCpuCount:4 -property:PlatformToolset=v142

compat/vcbuild/scripts/clink.pl

@@ -45,7 +45,7 @@ while (@ARGV) {
 		push(@args, "zlib.lib");
 	    }
 	} elsif ("$arg" eq "-liconv") {
-		push(@args, "libiconv.lib");
+		push(@args, "iconv.lib");
 	} elsif ("$arg" eq "-lcrypto") {
 		push(@args, "libcrypto.lib");
 	} elsif ("$arg" eq "-lssl") {

contrib/buildsystems/engine.pl

@@ -351,7 +351,7 @@ sub handleLinkLine
         } elsif ("$part" eq "-lexpat") {
             push(@libs, "libexpat.lib");
         } elsif ("$part" eq "-liconv") {
-            push(@libs, "libiconv.lib");
+            push(@libs, "iconv.lib");
         } elsif ($part =~ /^[-\/]/) {
             push(@lflags, $part);
         } elsif ($part =~ /\.(a|lib)$/) {