Add ptest for kernel samples.

Prerequisite:
1. Install package kernel-modules
2. enable ptest distro feature

Runtime testing(x86):
1. cd /usr/lib/linux-yocto/ptest
2. ./run-ptest

Testing result:
#####result#####
dma-example: PASS
bytestream-example: PASS
inttype-example: PASS
record-example: PASS
kobject-example: PASS
kset-example: PASS
trace-events-sample: PASS
trace-printk: PASS
kprobe_example: PASS
kretprobe_example: PASS

The following changes since commit 719d068bde55ef29a3468bc0779d4cb0c11e8c1d:

bitbake: fetch2: fix import error for Python 3.6.5 (2018-05-29 21:07:46 +0100)

are available in the git repository at:

https://github.com/DengkeDu/openembedded-core.git dengke/dev
https://github.com//tree/dengke/dev

Dengke Du (1):
linux-yocto: add ptest support

meta/recipes-kernel/linux/files/run-ptest | 138 ++++++++++++++++++++++++++
meta/recipes-kernel/linux/linux-yocto.inc | 8 ++
meta/recipes-kernel/linux/linux-yocto_4.14.bb | 2 +-
3 files changed, 147 insertions(+), 1 deletion(-)
create mode 100644 meta/recipes-kernel/linux/files/run-ptest

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2.7.4