[lld] r175657 - [ELF][Writer] Add .interp section.

[Sean Silva]

+  virtual StringRef getInterpreter() const {
+    return "/lib64/ld-linux-x86-64.so.2";
+  }
+

I don't think our FreeBSD friends are going to be too happy about
this. At least leave a FIXME.

-- Sean Silva