[FS#1433] Firmware can not be compiled with gcc 8

[LEDE Bugs]

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

User who did this - Aleksey (ambientsummer) 

Attached to Project - OpenWrt/LEDE Project
Summary - Firmware can not be compiled with gcc 8
Task Type - Build Failure
Category - Toolchain
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Host: Fedora 28 with GCC 8.0.1
Openwrt/LEDE: current trunk

[user@ openwrt]$ make prereq 
Checking 'working-make'... ok.
Checking 'case-sensitive-fs'... ok.
Checking 'proper-umask'... ok.
Checking 'gcc'... failed.
Checking 'working-gcc'... ok.
Checking 'g++'... failed.
Checking 'working-g++'... ok.
Checking 'ncurses'... ok.
Checking 'zlib'... ok.
Checking 'perl-thread-queue'... ok.
Checking 'tar'... ok.
Checking 'find'... ok.
Checking 'bash'... ok.
Checking 'patch'... ok.
Checking 'diff'... ok.
Checking 'cp'... ok.
Checking 'seq'... ok.
Checking 'awk'... ok.
Checking 'grep'... ok.
Checking 'getopt'... ok.
Checking 'stat'... ok.
Checking 'unzip'... ok.
Checking 'bzip2'... ok.
Checking 'wget'... ok.
Checking 'perl'... ok.
Checking 'python'... ok.
Checking 'git'... ok.
Checking 'file'... ok.
Checking 'ldconfig-stub'... ok.

Build dependency: Please install the GNU C Compiler (gcc) 4.8 or later cc -dumpversion | grep -E '(4\.[8-9]|5\.?[0-9]?|6\.?[0-9]?|7\.?[0-9]?)'
Build dependency: Please install the GNU C++ Compiler (g++) 4.8 or later g++ -dumpversion | grep -E '(4\.[8-9]|5\.?[0-9]?|6\.?[0-9]?|7\.?[0-9]?)'

Prerequisite check failed. Use FORCE=1 to override.
make[1]: *** [/home/user/openwrt/include/toplevel.mk:168: staging_dir/host/.prereq-build] Error 1
make: *** [/home/user/openwrt/include/toplevel.mk:83: prepare-tmpinfo] Error 2

More information can be found at the following URL:
https://bugs.openwrt.org/index.php?do=details&task_id=1433