[patch][pr22217] Use the most recent decl for mangling

[Rafael Espíndola]

> It is also a tentative definition in the corresponding case with
> __attribute__((section)). In that case, both GCC and Clang silently
> ignore the attribute.

That is not what I am seeing with gcc. Given

int pr22217_foo;
int *b = &pr22217_foo;
extern int pr22217_foo __attribute__((section("zed")));

It produces

.section zed,"aw", at progbits
.align 4
.type pr22217_foo, @object
.size pr22217_foo, 4
pr22217_foo:

I am testing with gcc 4.9.2.

Cheers,
Rafael