package/bash: use --bindir instead of exec_prefix=

package/bash: use --bindir instead of exec_prefix=

We want bash to be installed as /bin/bash. For ages, Buildroot has
been doing this by overriding exec_prefix at install time. First of
all, it would be preferred to do this at configure time. But also,
overriding exec_prefix not only changes where "bash" goes, but also
where the pkgconfig file goes. Due to this, bash.pc goes into
/lib/pkgconfig/, and doesn't get removed by target-finalize.

Since all we want is to have 'bash' as /bin/bash, simply pass
--bindir=/bin at configure time. This allows to use the default target
installation logic for autotools-package. We keep a post-install
target hook to remove /bin/bashbug.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>