perf: make a copy of kernel source to perf workdir

Since perf contaminates linux shared workdir, it probably caused
kernel-devsrc compile failure at world build.
...
|0 blocks
|cpio: ./tools/perf/arch/arm/util/sedr7ORqk: Cannot stat:
No such file or directory
|0 blocks
...
cpio tried to find a file at ${S}/tools/perf and failed
if the input list is not valid.

Make a copy of kernel shared source directory into a perf workdir
could fix the issue.

Drop `Fix for rebuilding' which is obsolete

[YOCTO #10880]

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>

0 files changed, 0 insertions, 0 deletions