[FS#1296] ar71xx doesnt build with gcc7

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - MartB (MartB) 

Attached to Project - OpenWrt/LEDE Project
Summary - ar71xx doesnt build with gcc7
Task Type - Bug Report
Category - Kernel
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - High
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - ar71xx UAP AC PRO
Latest openwrt master
Just built it with gcc7 => error.

Patch that fixed these upstream specific to 4.9:
https://patchwork.kernel.org/patch/10181291/

Probably worth waiting but i wanted to post this for reference if anyone comes across this.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1296