bash: Make it possible to run bash 3.2.48 instead of 4.2.

bash: Make it possible to run bash 3.2.48 instead of 4.2.

bash-3.2.48 did not provide the linking from sh to bash, making it unusable.
Moving the license part out of the bash.inc file, and into bash_4.2.bb file makes
us able to use that file also for bash_3.2.48.bb, which makes maintaining both
at the same time a lot easier.

(From OE-Core rev: e7b82cb4d107bfbfa5c939d406dd6ce6615b24e1)

Signed-off-by: Martin Ertsaas <mertsas@cisco.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>