[libc++/abi] Revert "[libc++] Move the weak symbols list to libc++abi"

This reverts commit c7d4aa7. I am still investigating the issue,
but it looks like that commit has an interaction with ld64 that causes
new/delete weak re-exports not to work properly anymore. This is weird
because this commit did not touch the exports of new/delete -- I am
still investigating.

Author: ldionne

libcxx/lib/weak.exp

@@ -0,0 +1,16 @@
+__ZTISt10bad_typeid
+__ZTISt11logic_error
+__ZTISt11range_error
+__ZTISt12domain_error
+__ZTISt12length_error
+__ZTISt12out_of_range
+__ZTISt13bad_exception
+__ZTISt13runtime_error
+__ZTISt14overflow_error
+__ZTISt15underflow_error
+__ZTISt16invalid_argument
+__ZTISt16nested_exception
+__ZTISt20bad_array_new_length
+__ZTISt8bad_cast
+__ZTISt9bad_alloc
+__ZTISt9exception

libcxx/src/CMakeLists.txt

@@ -210,7 +210,8 @@ if (LIBCXX_ENABLE_SHARED)
     target_link_libraries(cxx_shared PRIVATE
       "-Wl,-unexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/libc++unexp.exp"
       "-Wl,-reexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/libc++abi.v${LIBCXX_LIBCPPABI_VERSION}.exp"
-      "-Wl,-force_symbols_not_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/notweak.exp")
+      "-Wl,-force_symbols_not_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/notweak.exp"
+      "-Wl,-force_symbols_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/weak.exp")
 
     if (NOT LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS)
       target_link_libraries(cxx_shared PRIVATE

libcxxabi/lib/weak.exp

@@ -214,8 +214,6 @@ if (LIBCXXABI_ENABLE_SHARED)
 
     export_symbols("${CMAKE_CURRENT_SOURCE_DIR}/../lib/itanium-base.exp")
 
-    target_link_libraries(cxxabi_shared PRIVATE "-Wl,-force_symbols_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/weak.exp")
-
     if (LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS)
       export_symbols("${CMAKE_CURRENT_SOURCE_DIR}/../lib/new-delete.exp")
     endif()