CMake: Correct C++ Boost dependencies for Windows

With the new compiled Boost on the Windows machine, there is no need to add
zlib, bzip2, lzma, and zstd as extra dependencies. The compiled Boost binaries
include `libboost_zlib` and `libboost_bzip2` (lzma and zstd are not required).

Related to issue #133

cmake/BornAgain/Dependences.cmake

@@ -58,33 +58,20 @@ add_definitions(-DBOOST_UUID_FORCE_AUTO_LINK) # line is needed to link bcrypt fo
 
 # Boost component libraries (do not list headers here)
 set(boost_libraries_required iostreams program_options)
+# NOTE: `FindBoost` CMake module internally adds Boost::regex as an extra dependency for Boost::iostream
+
 if(WIN32)
-    # system seems to be indirectly required
-    list(APPEND boost_libraries_required system)
-    find_package(BZip2 REQUIRED)
-    find_package(ZLIB REQUIRED)
-    find_package(LibLZMA REQUIRED)
-    find_library(ZSTD_LIBRARY NAMES zstd)
+    # On Windows, additional libaries are required for Boost::iostream
+    list(APPEND boost_libraries_required zlib bzip2)
 endif()
+
+message(STATUS "Boost required libraries: ${boost_libraries_required}")
 find_package(Boost 1.65.1 COMPONENTS ${boost_libraries_required})
 message(STATUS "Boost: includes at ${Boost_INCLUDE_DIRS}, libraries at ${Boost_LIBRARY_DIRS}")
 if(NOT Boost_FOUND)
     message(FATAL_ERROR "Not all required Boost component libraries were found")
 endif()
 
-# requires these libs in target_link_libraries for win only
-set(Boost_Additional_Libraries "")
-if(WIN32)
-    list(APPEND Boost_Additional_Libraries ${BZIP2_LIBRARIES} ${ZLIB_LIBRARIES} ${LIBLZMA_LIBRARIES} ${ZSTD_LIBRARY})
-endif()
-
-if(Boost_Additional_Libraries)
-    message(STATUS "Additional libraries required for Boost:")
-    foreach(lib ${Boost_Additional_Libraries})
-        message("    ${lib}")
-    endforeach()
-endif()
-
 # === optional packages ===
 
 # --- MPI support ---