How to run FFI extension modules (.so files) made by Golang?

I can't make the FFI (Foreign Function Interface) work.

$ docker run --rm -it test:local php /app/sample.php
Fatal error: Uncaught FFI\Exception: Failed loading '/usr/local/lib/php/extensions/no-debug-non-zts-20200804/libutil.so' in /app/sample.php:6
Stack trace:
#0 /app/sample.php(6): FFI::cdef('void print(char...', '/usr/local/lib/...')
#1 {main}
  thrown in /app/sample.php on line 6

Go source code
- https://github.com/eislambey/php-ffi-go-example
sample.php

<?php

$util = FFI::cdef(
    "void print(char* p0);
    int sum(int p0, int p1);",
    "/usr/local/lib/php/extensions/no-debug-non-zts-20200804/libutil.so"
);

$util->print(
    (string) $util->sum(2, 4)
);

Dockerfile (Multi-state-build)

FROM golang:alpine AS builder

RUN \
    apk --no-cache add \
        git \
        gcc \
        musl-dev \
    && git clone https://github.com/eislambey/php-ffi-go-example.git /go/src

RUN \
    cd /go/src && \
    GOOS=linux go build -o libutil.so -buildmode=c-shared util.go

FROM keinos/php8-jit:latest

USER root

COPY sample.php /app/sample.php
COPY --from=builder /go/src/libutil.h /usr/local/lib/php/extensions/no-debug-non-zts-20200804/libutil.h
COPY --from=builder /go/src/libutil.so /usr/local/lib/php/extensions/no-debug-non-zts-20200804/libutil.so

RUN \
    apk --no-cache add \
        libffi-dev \
        # needs for "stddef.h"
        gcc \
        # requirement for ld-musl-x86_64.so.1
        musl-dev \
    && chmod 0755 /usr/local/lib/php/extensions/no-debug-non-zts-20200804/libutil.*

Result of php -i

$ docker run --rm test:local php -i | grep ffi
Configure Command =>  './configure'  '--build=x86_64-linux-musl' '--with-config-file-path=/usr/local/etc/php' '--with-config-file-scan-dir=/usr/local/etc/php/conf.d' '--enable-option-checking=fatal' '--with-mhash' '--enable-ftp' '--enable-mbstring' '--enable-mysqlnd' '--with-password-argon2' '--with-sodium=shared' '--with-pdo-sqlite=/usr' '--with-sqlite3=/usr' '--with-openssl=/usr' '--with-system-ciphers' '--with-ffi' '--enable-gd' '--with-external-gd' '--with-webp' '--with-jpeg' '--with-xpm' '--with-freetype' '--with-curl' '--with-libedit' '--with-zlib' '--with-pear' '--enable-soap' '--enable-pcntl' '--enable-opcache' '--enable-sockets' 'build_alias=x86_64-linux-musl' 'CPPFLAGS='
ffi.enable => preload => preload
ffi.preload => no value => no value

PHP Extension dir

$  docker run --rm test:local php -i | grep extension_dir
extension_dir => /usr/local/lib/php/extensions/no-debug-non-zts-20200804 => /usr/local/lib/php/extensions/no-debug-non-zts-20200804
sqlite3.extension_dir => no value => no value

KEINOS / Dockerfile_of_PHP8-JIT

How to run FFI extension modules (.so files) made by Golang? #21