MinGW: Disable VST3 builds under MinGW

extras/Build/CMake/JUCEUtils.cmake

@@ -304,7 +304,11 @@ function(_juce_get_platform_plugin_kinds out)
     endif()
 
     if(NOT CMAKE_SYSTEM_NAME STREQUAL "iOS" AND NOT CMAKE_SYSTEM_NAME STREQUAL "Android")
-        list(APPEND result AAX Unity VST VST3)
+        list(APPEND result AAX Unity VST)
+
+        if(NOT MINGW AND NOT MSYS)
+            list(APPEND result VST3)
+        endif()
     endif()
 
     set(${out} ${result} PARENT_SCOPE)