scripted-diff: Use C.UTF-8 locale in Guix scripts

The C.UTF-8 locale is set by default in `guix shell`, and there is no
reason to avoid it nowadays. This change also silences superfluous
warnings from Qt tools, making build logs cleaner and other issues
easier to spot.

Locales in the `guix-*` launch scripts have been updated as well for
consistency with the rest of the codebase.

-BEGIN VERIFY SCRIPT-

sed -i "s/\<export LC_ALL=C\>/export LC_ALL=C.UTF-8/g" \
 $( git grep -l "export LC_ALL=C" ./contrib/guix/* )

-END VERIFY SCRIPT-

contrib/guix/guix-attest

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -e -o pipefail
 
 # Source the common prelude, which:

contrib/guix/guix-build

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -o errexit -o pipefail
 
 # Source the common prelude, which:

contrib/guix/guix-clean

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -e -o pipefail
 
 # Source the common prelude, which:

contrib/guix/guix-codesign

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -e -o pipefail
 
 # Source the common prelude, which:

contrib/guix/guix-verify

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -e -o pipefail
 
 # Source the common prelude, which:

contrib/guix/libexec/build_linux.sh

@@ -2,7 +2,7 @@
 # Copyright (c) The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit.
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -o errexit -o pipefail
 
 # shellcheck source=setup.sh

contrib/guix/libexec/build_linux_gui.sh

@@ -2,7 +2,7 @@
 # Copyright (c) The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit.
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -o errexit -o pipefail
 
 # shellcheck source=setup.sh

contrib/guix/libexec/build_macos.sh

@@ -2,7 +2,7 @@
 # Copyright (c) The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit.
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -o errexit -o pipefail
 
 # shellcheck source=setup.sh

contrib/guix/libexec/build_macos_gui.sh

@@ -2,7 +2,7 @@
 # Copyright (c) The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit.
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -o errexit -o pipefail
 
 # shellcheck source=setup.sh

contrib/guix/libexec/build_win.sh

@@ -2,7 +2,7 @@
 # Copyright (c) The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit.
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -o errexit -o pipefail
 
 # shellcheck source=setup.sh

contrib/guix/libexec/build_win_gui.sh

@@ -2,7 +2,7 @@
 # Copyright (c) The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit.
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -o errexit -o pipefail
 
 # shellcheck source=setup.sh

contrib/guix/libexec/codesign.sh

@@ -2,7 +2,7 @@
 # Copyright (c) 2021-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -e -o pipefail
 
 # Environment variables for determinism

contrib/guix/libexec/package.sh

@@ -2,7 +2,7 @@
 # Copyright (c) The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit.
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -e -o pipefail
 
 (

contrib/guix/libexec/prelude.bash

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -o errexit -o pipefail
 
 source contrib/shell/realpath.bash

contrib/guix/libexec/setup.sh

@@ -2,7 +2,7 @@
 # Copyright (c) The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit.
-export LC_ALL=C
+export LC_ALL=C.UTF-8
 set -o errexit -o pipefail
 
 # Environment variables for determinism