fix(steps-guix): add libffi build before guile-2.2.4 and wire explicit libffi pkg-config flags

steps-guix/libffi-3.5.2/pass1.sh

@@ -0,0 +1,19 @@
+# SPDX-FileCopyrightText: 2022 Andrius Štikonas <andrius@stikonas.eu>
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+src_prepare() {
+    rm doc/libffi.{pdf,info}
+
+    autoreconf-2.71 -fi
+}
+
+src_configure() {
+    ./configure \
+        --prefix="${PREFIX}" \
+        --libdir="${LIBDIR}" \
+        --build="${TARGET}" \
+        --disable-shared \
+        --with-gcc-arch=generic \
+        --enable-pax_emutramp
+}

steps-guix/libffi-3.5.2/sources

@@ -0,0 +1 @@
+f https://github.com/libffi/libffi/releases/download/v3.5.2/libffi-3.5.2.tar.gz f3a3082a23b37c293a4fcd1053147b371f2ff91fa7ea1b2a52e335676bac82dc