Link error building a .m tool with clang on Linux

[Lobron, David]

Hello gnustep,

I recently picked up the latest libobjc2 and gnustep-base libraries, while 
working on a clang build of some ObjC and ObjC++ programs on Ubuntu Linux.  The 
latest codebases solved a number of other problems I was having, but a symbol 
is now missing in a shared library that some sub-programs use, causing those 
programs not to link.  Here is a representative example:

/home/dlobron/build/clangport/akamai/llvm/llvm-5.0.0.install/bin/clang  
-rdynamic     -m64  -rdynamic  -pthread  -fexceptions 
-fobjc-runtime=gnustep-1.8 -fblocks -o obj/list2tree \
                ./obj/list2tree.obj/list2tree.m.o \
                  
-L/home/dlobron/build/clangport/akamai/AkamaiKit/Tools/../../common/lib 
-L../AkamaiKit.framework/Versions/Current/.    
-L/home/dlobron/GNUstep/Library/Libraries 
-L/home/dlobron/build/clangport/akamai/common/GNUstep/Local/Library/Libraries 
-L/home/dlobron/build/clangport/akamai/common/GNUstep/System/Library/Libraries  
 -lAkamaiKit -lXMLKit -lopenssl   -lgnustep-base   -lpthread -lobjc 
-fobjc-nonfragile-abi   -lm
../AkamaiKit.framework/Versions/Current/./libAkamaiKit.so: undefined reference 
to `vtable for gnustep::libobjc::__objc_class_type_info'
clang-6.0: error: linker command failed with exit code 1 (use -v to see 
invocation)

Here, libAkamaiKit.so is a shared library.  Upon examination, the symbol in 
question is indeed present and not defined:

U vtable for gnustep::libobjc::__objc_class_type_info

I examined some builds that used my previous versions of gnustep-base and 
libobjc2.  In those builds, the above symbol does not appear at all in the 
shared library, libAkamaiKit.so.

Does anyone know of recent changes in gnustep-base or libobjc2 that might cause 
this?  Should I add a library in my link command?  I'm already linking 
libobjc.so, and I confirmed that no __objc_class_type_info symbol is present 
there.  I'm also working on a minimal reproducer.

Thank you,

David