Backporting ARC patch to gcc7.x

[Claudiu Zissulescu]

> We've generally considered those clauses under the umbrella of the port
> maintainers.

Thank you for your guidance. I've backported the patch using the gcc guideline:

>svn commit
Sending        .
Sending        gcc/ChangeLog
Sending        gcc/config.gcc
Sending        libgcc/ChangeLog
Sending        libgcc/config.host
Transmitting file data ....
Committed revision 254864.

Thank you,
Claudiu