fix bash shebangs

In the change set 6c045a999800c62368470938307951bb669f5afc the error
text for the old flag `--private-users-chown` was repurposed for the
new flag `--private-users-ownership=own` and while doing so the word
`may` was dropped leading to a grammatically incorrect error text.

src/basic/generate-af-list.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # SPDX-License-Identifier: LGPL-2.1-or-later
 set -eu
 set -o pipefail

src/basic/generate-arphrd-list.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # SPDX-License-Identifier: LGPL-2.1-or-later
 set -eu
 set -o pipefail

src/basic/generate-cap-list.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # SPDX-License-Identifier: LGPL-2.1-or-later
 set -eu
 set -o pipefail

src/basic/generate-errno-list.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # SPDX-License-Identifier: LGPL-2.1-or-later
 set -eu
 set -o pipefail

src/libsystemd/sd-journal/generate-audit_type-list.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # SPDX-License-Identifier: LGPL-2.1-or-later
 set -eu
 set -o pipefail

src/nspawn/nspawn.c

@@ -453,7 +453,7 @@ static int custom_mount_check_all(void) {
                 if (path_equal(m->destination, "/") && arg_userns_mode != USER_NAMESPACE_NO) {
                         if (arg_userns_ownership != USER_NAMESPACE_OWNERSHIP_OFF)
                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
-                                                       "--private-users-ownership=own not be combined with custom root mounts.");
+                                                       "--private-users-ownership=own may not be combined with custom root mounts.");
                         if (arg_uid_shift == UID_INVALID)
                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
                                                        "--private-users with automatic UID shift may not be combined with custom root mounts.");

src/shared/generate-ip-protocol-list.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
 set -eu

src/udev/generate-keyboard-keys-list.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # SPDX-License-Identifier: LGPL-2.1-or-later
 set -eu
 set -o pipefail

tools/meson-apply-m4.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # SPDX-License-Identifier: LGPL-2.1-or-later
 set -eu