Build failure: -Wno-unused-const-variable DNE on old GCC

[Joe Perches]

On Thu, 2016-01-07 at 10:54 -0800, Brian Norris wrote:
> Hi,
> 
> I'm using a GCC 4.6.3 compiler for some compile tests, and I noticed
> that commit 2cd55c68c0a4 ("cxl: Fix build failure due to -Wunused-variable
> behaviour change") breaks my builds, because the
> -Wno-unused-const-variable doesn't exist on GCC 4.6.3.
> 
>   drivers/misc/cxl/base.c: At top level:
>   cc1: error: unrecognized command line option "-Wno-unused-const-variable" [-Werror]
> 
> Any thoughts on how to best fix this? I'd like not to have to scrounge
> up a new cross compiler just for build tests.

drivers/misc/cxl/Makefile:ccflags-y := -Werror -Wno-unused-const-variable

You could take that -Wno-unused-const-variable out of the
Makefile or maybe add something like:

$(call cc-ifversion, -ge, 0530, -Wno-unused-const-variable)

or whatever gcc version actually added that unused-const-variable check