When a symbol in a comdat/linkonce section has different visibility in different
files, linker doesn't merge symbol visibility:

bash-3.1$ cat foo.c
int foo __attribute__ ((section (".gnu.linkonce.d.1"))) = 1;
int
__attribute__ ((section (".gnu.linkonce.t.1")))
bar ()
{
  return 1;
}
bash-3.1$ cat bar.c
int foo __attribute__ ((section (".gnu.linkonce.d.1"),
                        visibility ("hidden"))) = 1;
int
__attribute__ ((section (".gnu.linkonce.t.1"), visibility ("hidden")))
bar ()
{
  return 1;
}
int
get_foo ()
{
  return foo;
}
int
get_bar ()
{
  return bar ();
}
bash-3.1$ make
gcc -fPIC -O   -c -o bar.o bar.c
gcc -fPIC -O   -c -o foo.o foo.c
ld -shared -o lib1.so bar.o foo.o
ld -shared -o lib2.so foo.o bar.o
ld: bar.o: relocation R_X86_64_PC32 against `foo' can not be used when making a
shared object; recompile with -fPIC
ld: final link failed: Bad value
make: *** [lib2.so] Error 1
bash-3.1$ 

Should we handle this case?