module.bbclass: add lock to prevent error bulding ext modules
When external modules are built, files in $STAGING_KERNEL_DIR/scripts/basic will/can get
rebuilt.
This raises a potential race condition. Prevent this by adding a lock around the
do_make_scripts() function. Further, make sure that the kernel has been installed
to the sysroot, prior to executing this new task.
(From OE-Core rev:
8681b82e8b466929205edde7ba479f3ac1a6143e)
Signed-off-by: Anders Darander <anders@chargestorm.se>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
