populate_sdk_base.bbclass: Improve debugging capabilities for SDK installer

populate_sdk_base.bbclass: Improve debugging capabilities for SDK installer

After having to debug the SDK installer a few times in
addition to the relocation code the following patch was created
to improve the capabilities around debugging the SDK installer.

1) Add a verbose mode -D which set a set -x to see what
   the SDK installer is doing.

2) Add a mode -S to save the relocation scripts for the purpose
   of debugging them in conjunction with -D

3) Add a mode -R to not execute the relocation scripts for the
   purpose of debugging the relocations.

(From OE-Core rev: 0e6dd19b9736d2a8ae7c0f0ab124337d579b8f06)

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>