Windows : require at least VS2019 for MSVC.

This will  avoid some errors on appveyor, due to outdated SDKs.

appveyor.yml

@@ -3,7 +3,7 @@ version: build-{build}~branch-{branch}
 before_build:
   - md %APPVEYOR_BUILD_FOLDER%\win_build
   - cd %APPVEYOR_BUILD_FOLDER%\win_build
-  - cmake ..  -G "Visual Studio 15 2017 Win64" -DWITH_UNIT_TESTS=0 -DWITH_MARIABACKUP=0 -DMYSQL_MAINTAINER_MODE=ERR -DPLUGIN_ROCKSDB=NO -DPLUGIN_CONNECT=NO -DBISON_EXECUTABLE=C:\cygwin64\bin\bison
+  - cmake .. -DWITH_UNIT_TESTS=0 -DWITH_MARIABACKUP=0 -DMYSQL_MAINTAINER_MODE=ERR -DPLUGIN_ROCKSDB=NO -DPLUGIN_CONNECT=NO -DBISON_EXECUTABLE=C:\cygwin64\bin\bison
 
 build:
   project: win_build\MySQL.sln
@@ -18,4 +18,4 @@ test_script:
   - cd %APPVEYOR_BUILD_FOLDER%\win_build\mysql-test
   - perl mysql-test-run.pl --force --max-test-fail=10 --parallel=4 --testcase-timeout=10 --skip-test-list=unstable-tests --suite=main
 
-image: Visual Studio 2017
+image: Visual Studio 2019

cmake/os/Windows.cmake

@@ -110,6 +110,9 @@ ENDMACRO()
 
 
 IF(MSVC)
+  IF(MSVC_VERSION LESS 1920)
+    MESSAGE(FATAL_ERROR "Visual Studio q2019 or later is required")
+  ENDIF()
   # Disable mingw based pkg-config found in Strawberry perl
   SET(PKG_CONFIG_EXECUTABLE 0 CACHE INTERNAL "")