[OE-core] Change to kernel.bbclass broke kernel build when gcc does not support -ffile-prefix-map

[Andrew Goodbody]

> From: Bystricky, Juro [mailto:juro.bystricky at intel.com]
> 
> Yes, the issue was reported by others as well, it should be fixed by this patch:
> 
> https://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?h=master-
> next&id=2b7646a113cca7698d8484fe14bdbb8683a5f8ab
> 
> > From: Andrew Goodbody [mailto:andrew.goodbody at cambrionix.com]
> >
> > My build uses a version of gcc that does not support -ffile-prefix-map and
> > this is now broken after I updated the tree to include the latest commit to
> > kernel.bbclass "improve reproducibility" 012a70da7ae0617 by Juro
> Bystricky.
> >
> > The patch introduces the line
> > cc_option_supported=`${KERNEL_CC} -Q --help=joined | grep ffile-prefix-
> map`
> > When gcc does not support -ffile-prefix-map, the grep will exit with a non-
> > zero return code which is caught and causes the do_compile step to fail.
> >
> > Thanks,
> > Andrew

Great, thanks,
Andrew