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

[Bystricky, Juro]

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


> -----Original Message-----
> From: Andrew Goodbody [mailto:andrew.goodbody at cambrionix.com]
> Sent: Tuesday, August 22, 2017 5:19 AM
> To: openembedded-core at lists.openembedded.org
> Cc: Bystricky, Juro <juro.bystricky at intel.com>
> Subject: Change to kernel.bbclass broke kernel build when gcc does not
> support -ffile-prefix-map
> 
> 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