fix(guix): add dedicated build step to compile and run loopback bind helper before python server

steps-guix/loopback-bind-127001/pass1.sh

@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+src_prepare() {
+    default
+}
+
+src_configure() {
+    :
+}
+
+src_compile() {
+    gcc -O2 -std=c99 -Wall -Wextra -Werror \
+        -o /tmp/loopback-bind-127001 \
+        loopback-bind-127001.c
+
+    /tmp/loopback-bind-127001
+}
+
+src_install() {
+    install -D -m 0644 /dev/null "${DESTDIR}/usr/share/loopback-bind-127001.done"
+}