If we chdir(), do the chdir back to the original directory in a finally
block so they always run.
(From OE-Core rev: cdc40292818683b6df1c814498c7589450a163fa)
Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>