Appveyor build - Test schannel client / openssl server combination.

This is not tested elsewhere, and apparently, there are some issues.

appveyor.yml

@@ -21,7 +21,7 @@ build_script:
   - set PATH=%OPENSSL_ROOT_DIR%;%PATH%
   - set GENERATOR=-GNinja
   - call "C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars64.bat"
-  - cmake -E time cmake %GENERATOR% .. -DWITH_SSL=system -DHAVE_OPENSSL_APPLINK_C=1 -DOPENSSL_ROOT_DIR=%OPENSSL_ROOT_DIR% -DCMAKE_BUILD_TYPE=%BUILD_TYPE% -DMYSQL_MAINTAINER_MODE=ERR -DFAST_BUILD=1 -DBISON_EXECUTABLE=C:\cygwin64\bin\bison.exe -DPLUGIN_PERFSCHEMA=NO -DPLUGIN_FEEDBACK=NO
+  - cmake -E time cmake %GENERATOR% .. -DCONC_WITH_SSL=SCHANNEL -DWITH_SSL=system -DHAVE_OPENSSL_APPLINK_C=1 -DOPENSSL_ROOT_DIR=%OPENSSL_ROOT_DIR% -DCMAKE_BUILD_TYPE=%BUILD_TYPE% -DMYSQL_MAINTAINER_MODE=ERR -DFAST_BUILD=1 -DBISON_EXECUTABLE=C:\cygwin64\bin\bison.exe -DPLUGIN_PERFSCHEMA=NO -DPLUGIN_FEEDBACK=NO
   - set /A jobs=2*%NUMBER_OF_PROCESSORS%
   - cmake -E time cmake --build . -j %jobs% --config %BUILD_TYPE% --target minbuild