libarchive: Drop LIBARCHIVE_ADDITIONAL_LIBS, CMake does not need it

Utilities/cmlibarchive/CMakeLists.txt

@@ -1291,12 +1291,6 @@ CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/build/cmake/config.h.in
 INCLUDE_DIRECTORIES(BEFORE ${CMAKE_CURRENT_BINARY_DIR})
 ADD_DEFINITIONS(-DHAVE_CONFIG_H)
 
-#
-# Expose ADDITIONAL_LIBS for projects using libarchive as a subdirectory
-# and linking against archive_static.
-#
-set(LIBARCHIVE_ADDITIONAL_LIBS ${ADDITIONAL_LIBS} CACHE INTERNAL "libarchive dependencies")
-
 #
 # Register installation of PDF documents.
 #