[llvm-readobj] - An attempt to fix BB.

This adds the `template` keyword for 'getAsArrayRef' calls.

An example of error:
/b/1/openmp-gcc-x86_64-linux-debian/llvm.src/llvm/tools/llvm-readobj/ELFDumper.cpp:4491:50: error: use 'template' keyword to treat 'getAsArrayRef' as a dependent template name
    for (const Elf_Rel &Rel : this->DynRelRegion.getAsArrayRef<Elf_Rel>())