steps-guix: add argp-standalone-1.4.1 kernel-toolchain step

- add steps-guix/argp-standalone-1.4.1/pass1.sh
- run autoreconf before configure
- build/install with standard flow into /kernel-toolchain
- wire argp-standalone-1.4.1 into steps-guix manifest after gcc
- prepare argp for later kernel-side elfutils dependency

steps-guix/argp-standalone-1.4.1/pass1.sh

@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+# Build argp-standalone for the kernel toolchain sysroot. This is used by
+# later kernel-side dependencies (for example elfutils).
+: "${KERNEL_TARGET:=x86_64-unknown-linux-musl}"
+: "${KERNEL_SYSROOT:=/kernel-toolchain}"
+
+src_prepare() {
+    default
+    autoreconf -fi
+}
+
+src_configure() {
+    export PATH="${KERNEL_SYSROOT}/bin:${PATH}"
+
+    mkdir build
+    cd build
+
+    ../configure \
+        --prefix="${KERNEL_SYSROOT}" \
+        --libdir="${KERNEL_SYSROOT}/lib" \
+        --build="${TARGET}" \
+        --host="${KERNEL_TARGET}" \
+        --target="${KERNEL_TARGET}"
+}
+
+src_compile() {
+    default_src_compile
+}
+
+src_install() {
+    make "${MAKEJOBS}" install \
+        DESTDIR="${DESTDIR}" \
+        prefix="${KERNEL_SYSROOT}" \
+        libdir="${KERNEL_SYSROOT}/lib"
+}

steps-guix/argp-standalone-1.4.1/sources

@@ -0,0 +1 @@
+g https://github.com/ericonr/argp-standalone.git~743004c68e7358fb9cd4737450f2d9a34076aadf https://github.com/ericonr/argp-standalone/archive/743004c68e7358fb9cd4737450f2d9a34076aadf.tar.gz  a79f2a6fd6c68a423063ee53bc4afb6a5633a296a25764e5cc368c1e323a0997 argp-standalone-743004c6.tar.gz

steps-guix/manifest

@@ -5,3 +5,4 @@
 # We need a 64-bit kernel to enable Guix to run 64-bit programs.
 build: binutils-2.41
 build: gcc-15.2.0
+build: argp-standalone-1.4.1