break.i

void setValue(int v);
extern int value;

int main()
{
        setValue(42);
        return value;
}

gistfile1.txt

With -Bsymbolic-functions, it works as expected:

fvogt@linux-e202:/tmp/breakutils> gcc -fPIC -shared -Wl,-Bsymbolic-functions -Wl,--dynamic-list,lib.dynlist -o lib.so lib.i && readelf --dyn-syms -r lib.so | grep value
000000003fe8  000600000006 R_X86_64_GLOB_DAT 0000000000004024 value + 0
     6: 0000000000004024     4 OBJECT  GLOBAL DEFAULT   22 value
fvogt@linux-e202:/tmp/breakutils> gcc lib.so break.i -o break && LD_LIBRARY_PATH=$PWD ./break; echo $?
42

Without, the relocation is missing and setValue writes into a different value than main reads from:

fvogt@linux-e202:/tmp/breakutils> gcc -fPIC -shared -Wl,--dynamic-list,lib.dynlist -o lib.so lib.i && readelf --dyn-syms -r lib.so | grep value
     6: 0000000000004024     4 OBJECT  GLOBAL DEFAULT   22 value
fvogt@linux-e202:/tmp/breakutils> gcc lib.so break.i -o break && LD_LIBRARY_PATH=$PWD ./break; echo $?
0

lib.dynlist

{
     extern "C" {
         "setValue";
     };
};

lib.i

int value = 0;
void setValue(int v) {
  value = v;
}