Add arm64 clang-8 builds to linux-next

[mattface]

Add arm64 clang builds to linux-next, keeping gcc-7 as well.

This will only add 1 currently known failing build which is allmodconfig.

[gctucker]

@mattface I've run a test build using my gtucker test branch and there seems to be a bug in the build email reports. The top-level summary says that arm64 defconfig failed to build with gcc-8:

arm64:    aarch64-linux-gnu-gcc (Debian 8.2.0-11) 8.2.0

    defconfig: FAIL

but actually it failed with clang-8, as shown correctly in the details further down:

--------------------------------------------------------------------------------
defconfig (arm64, gcc-8) — PASS, 0 errors, 3 warnings, 0 section mismatches

Warnings:
    arch/arm64/boot/dts/rockchip/rk3399-gru-bob.dts:25.9-29.5: Warning (graph_port): /edp-panel/ports: graph port node name should be 'port'
    arch/arm64/boot/dts/rockchip/rk3399-gru-kevin.dts:46.9-50.5: Warning (graph_port): /edp-panel/ports: graph port node name should be 'port'
    arch/arm64/boot/dts/rockchip/rk3399-sapphire-excavator.dts:94.9-98.5: Warning (graph_port): /edp-panel/ports: graph port node name should be 'port'

--------------------------------------------------------------------------------
defconfig (arm64, clang-8) — FAIL, 20 errors, 45 warnings, 0 section mismatches

Full email report: https://termbin.com/vofgm

Sounds like this should be reported as an issue in Github, unless someone can explain what went wrong here.

[gctucker]

This was run with kernelci-backend version 2019.2.1 on staging.kernelci.org.

[mattface]

@gctucker Ok thats pretty bad and will be a blocker. I'll look into the email issues asap.

[gctucker]

The issue mentioned above seems to be intermittent btw, I've run another build and it seemed fine.

So I guess these are the things that need to be done before merging this PR:

• fix the bug in build reports described above, showing the wrong compiler version in the summary
• wait for build fixes to land in linux-next for arm64 clang-8, current status is that allmodconfig is failing to build and there's a warning in defconfig:
  https://staging.kernelci.org/build/next-clang/branch/master/kernel/next-20190306/
• run a test build on staging with this PR to confirm that it's doing what's expected

[gctucker]

@mattface Could you please resubmit this in https://github.com/kernelci/kernelci-core as we're shutting down the kernelci-core-staging repo this week?

Also it doesn't look like the build fix has made it into linux-next yet:
https://staging.kernelci.org/build/next-clang/branch/master/kernel/next-20190319/

[gctucker]

@mattface Please resubmit this PR in https://github.com/kernelci/kernelci-core as we're shutting down kernelci-core-staging today.

cc @broonie