RFA: Remove use of register keyword in libiberty.h

[Nick Alcock]

On 25 Jun 2020, Nick Clifton outgrape:

> Hi Ian, Hi Nick,
>
>   Comping the GOLD linker with Clang has started producing this error
>   message:
>
>     In file included from gold/archive.cc:29:
>     include/libiberty.h:646:25: error: 'register' storage class
>       specifier is deprecated and incompatible with C++17
>       [-Werror,-Wdeprecated-register]
>
>   So I would like to apply the patch below to fix this.  Is this OK ?

Yes please! This was copied straight from bsearch.c, so you probably
want to change bsearch.c and bsearch_r.c as well (just in case clang
ever finds itself needing to build bsearch_r out of libiberty).