https://sourceforge.net/p/rosegarden/bugs/1746/
https://bugs.gentoo.org/957755
fix compile with Qt built with QT_USE_PROTECTED_VISIBILITY
ROSEGARDENPRIVATE_LIB_MAKEDLL should only be defined for the shared library
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -9,7 +9,6 @@ configure_file(rosegarden-version.h.cmake ${CMAKE_CURRENT_BINARY_DIR}/rosegarden
 
 # Export macros
 configure_file(rosegardenprivate_export.h.cmake ${CMAKE_CURRENT_BINARY_DIR}/rosegardenprivate_export.h)
-add_definitions(-DROSEGARDENPRIVATE_LIB_MAKEDLL)
 
 # Define the include paths (-I...)
 include_directories(
@@ -851,6 +850,8 @@ add_library(rosegardenprivate ${RG_LIBRARY_TYPE}
    ${CMAKE_CURRENT_BINARY_DIR}/svnversion.h
 )
 
+target_compile_definitions(rosegardenprivate PRIVATE ROSEGARDENPRIVATE_LIB_MAKEDLL)
+
 # If we've got cmake 3.16.0 or greater, use precompiled headers.
 # Cuts build time almost in half.
 if(NOT ${CMAKE_VERSION} VERSION_LESS "3.16.0")