Fix Qt platform directory install in win64 build
Fix Qt platform directory install in win64 build

better solution might be `install (DIRECTORY "${QT_DLL_DIR}/../plugins/platforms" DESTINATION bin FILES_MATCHING PATTERN "*.*" PATTERN "*.dll" EXCLUDE)` but I'm not used to use this CMake option, just guessing.
grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas