The default ksh in OpenBSD throws the following error:
===
$ . hacking/env-setup
ksh: hacking/env-setup[23]: ${.sh.file}": bad substitution
[...]
===

The same error can be seen on Linux if pdksh is used.

cherry picked from https://github.com/ansible/ansible/pull/6899

For example, pdksh $0 contains '-ksh'.

The replaced code only created a text file called `1' in the
current directory, it did *not* redirect output.

POSIX section 2.7.4 defines here-documents.

Conflicts:
	hacking/env-setup

Conflicts:
	hacking/env-setup

Fixes #9991

Conflicts:
	hacking/env-setup

Conflicts:
	hacking/env-setup

hacking/env-setup now adds the configured library path in ANSIBLE_CONFIG
to the ANSIBLE_LIBRARY environment variable in addition to the previous
default of ANSIBLE_HOME/library.

This replaces #5950.

This fixes issue #5026. It used to work. The regression was
introduced in 2b3381de.

Signed-off-by: martin f. krafft <madduck@madduck.net>

This replaces double conditional brackets with single ones and gets ris
of bashisms, so that the tool should be sourcable from any POSIX shell.

Constructs like [ $foo = "$bar"* ] yield filesystem-globbing behaviour
according to POSIX. A compliant way is to use case statements.

Signed-off-by: martin f. krafft <madduck@madduck.net>

In case paths contain spaces, it's better to consistently quote
variables, and to use $() instead of `` for external invocations.

Signed-off-by: martin f. krafft <madduck@madduck.net>

dirname/basename do not need an external process, shell variable
expansion can be made to do the same a bit faster.

Signed-off-by: martin f. krafft <madduck@madduck.net>

The env-setup script is not intended to be run directly, so it does not
need a shebang line, which might even create the wrong expectations.

Signed-off-by: martin f. krafft <madduck@madduck.net>

'source' is actually a "bashism" and the POSIX-way of sourcing a file
uses the single dot (which is arguably less readable). Both yield the
same result, and since the script may now also be sourced from
within the hacking directory, this commit expands the usage synopsis
accordingly.

Signed-off-by: martin f. krafft <madduck@madduck.net>

Conflicts:
	hacking/env-setup

Bash needs a special case to determine the dirname of the sourced path
(the hacking dir), but in all other cases, using $0 allows the script to
be sourced also from within the hacking directory, not only from its
parent.

Signed-off-by: martin f. krafft <madduck@madduck.net>