cmake: support MSVS 2019

cmake/OpenCVDetectCXXCompiler.cmake

@@ -143,6 +143,8 @@ elseif(MSVC)
     set(OpenCV_RUNTIME vc14)
   elseif(MSVC_VERSION MATCHES "^191[0-9]$")
     set(OpenCV_RUNTIME vc15)
+  elseif(MSVC_VERSION MATCHES "^192[0-9]$")
+    set(OpenCV_RUNTIME vc16)
   else()
     message(WARNING "OpenCV does not recognize MSVC_VERSION \"${MSVC_VERSION}\". Cannot set OpenCV_RUNTIME")
   endif()

cmake/templates/OpenCVConfig.root-WIN32.cmake.in

@@ -113,6 +113,16 @@ elseif(MSVC)
     if(NOT has_VS2017)
       set(OpenCV_RUNTIME vc14) # selecting previous compatible runtime version
     endif()
+  elseif(MSVC_VERSION MATCHES "^192[0-9]$")
+    set(OpenCV_RUNTIME vc16)
+    check_one_config(has_VS2019)
+    if(NOT has_VS2019)
+      set(OpenCV_RUNTIME vc15) # selecting previous compatible runtime version
+      check_one_config(has_VS2017)
+      if(NOT has_VS2017)
+        set(OpenCV_RUNTIME vc14) # selecting previous compatible runtime version
+      endif()
+    endif()
   endif()
 elseif(MINGW)
   set(OpenCV_RUNTIME mingw)