core: link privately to libraries used only by libCore

This is to avoid direct linking to compression libraries
in libraries that link to libCore.

core/CMakeLists.txt

@@ -115,12 +115,19 @@ endif()
 add_subdirectory(rootcling_stage1)
 
 #-------------------------------------------------------------------------------
-ROOT_LINKER_LIBRARY(Core
-                    $<TARGET_OBJECTS:BaseTROOT>
-                    ${objectlibs}
-                    LIBRARIES PCRE::PCRE ${LZMA_LIBRARIES} xxHash::xxHash LZ4::LZ4 ZLIB::ZLIB
-                              ${CMAKE_DL_LIBS} ${CMAKE_THREAD_LIBS_INIT} ${corelinklibs}
-                    BUILTINS LZMA)
+ROOT_LINKER_LIBRARY(Core $<TARGET_OBJECTS:BaseTROOT> ${objectlibs} BUILTINS LZMA)
+
+target_link_libraries(Core
+  PRIVATE
+    PCRE::PCRE
+    ${LZMA_LIBRARIES}
+    xxHash::xxHash
+    LZ4::LZ4
+    ZLIB::ZLIB
+    ${CMAKE_DL_LIBS}
+    ${CMAKE_THREAD_LIBS_INIT}
+    ${corelinklibs}
+)
 
 if(cling)
   add_dependencies(Core CLING)