Bug#844439: gcc-6 broken for kernel development work

[Al Viro <viro@ZenIV.linux.org.uk>]

Package: gcc-6
Version: 6.2.0-10
Severity: important

gcc-6 as packaged is broken for normal use patterns when working on the
mainline kernel.  In particular, any git bisect session that strays into
4.8 and earlier requires rather unpleasant workarounds - either playing
with kbuild variables in command line, or, equally unpleasant, patching
Makefile on each bisection step and unpatching before moving to the
next one.

This is *NOT* about debian kernel packaging; what had been broken is
the use of gcc for mainline kernel development, which used to be
a supported use case until October.  And that definitely includes
building the kernels resulting from git bisect.  Unless you wish to
argue that kernel work is not supported anymore, I don't see any way
around Severity: important - "has a major effect on the usability
of a package, without rendering it completely unusable to everyone".