Add support for pkg-config

When pkg-config is installed and finds the libraries, use those rather than relying on Homebrew or bundling OpenSSL.

Fixes #2544

Author: baarde

bin/ruby-build

@@ -675,16 +675,16 @@ build_package_standard() {
     local ruby_semver="$(normalize_semver "${package_name#ruby-}")"
     if [[ "$RUBY_CONFIGURE_OPTS ${RUBY_CONFIGURE_OPTS_ARRAY[*]}" != *--with-readline-dir=* && "$ruby_semver" -lt 300300 ]]; then
       # Ruby 3.3+ does not need external readline: https://github.com/rbenv/ruby-build/issues/2330
-      use_homebrew_readline || use_freebsd_readline || true
+      use_pkgconfig_readline || use_homebrew_readline || use_freebsd_readline || true
     fi
     if [[ "$RUBY_CONFIGURE_OPTS ${RUBY_CONFIGURE_OPTS_ARRAY[*]}" != *--with-libffi-dir=* ]]; then
-      use_freebsd_libffi || true
+      use_pkgconfig_libffi || use_freebsd_libffi || true
     fi
     if [[ "$RUBY_CONFIGURE_OPTS ${RUBY_CONFIGURE_OPTS_ARRAY[*]}" != *--with-libyaml-dir=* ]]; then
-      use_homebrew_yaml || use_freebsd_yaml || true
+      use_pkgconfig_yaml || use_homebrew_yaml || use_freebsd_yaml || true
     fi
     if [[ "$RUBY_CONFIGURE_OPTS ${RUBY_CONFIGURE_OPTS_ARRAY[*]}" != *--with-gmp-dir=* ]]; then
-      use_homebrew_gmp || true
+      use_pkgconfig_gmp || use_homebrew_gmp || true
     fi
     if [[ "$RUBY_CONFIGURE_OPTS ${RUBY_CONFIGURE_OPTS_ARRAY[*]}" != *--with-openssl-dir=* ]]; then
       if is_freebsd && [ -f /usr/local/include/openssl/ssl.h ]; then
@@ -1027,9 +1027,20 @@ require_llvm() {
 
 needs_yaml() {
   [[ "$RUBY_CONFIGURE_OPTS ${RUBY_CONFIGURE_OPTS_ARRAY[*]}" != *--with-libyaml-dir=* ]] &&
+  ! use_pkgconfig_yaml &&
   ! use_homebrew_yaml
 }
 
+use_pkgconfig_yaml() {
+  local libdir
+  libdir="$(pkg-config --variable=prefix yaml-0.1 2>/dev/null || true)"
+  if [ -d "$libdir" ]; then
+    package_option ruby configure --with-libyaml-dir="$libdir"
+  else
+    return 1
+  fi
+}
+
 use_homebrew_yaml() {
   local libdir
   libdir="$(brew --prefix libyaml 2>/dev/null || true)"
@@ -1051,6 +1062,16 @@ use_freebsd_yaml() {
   fi
 }
 
+use_pkgconfig_gmp() {
+  local libdir
+  libdir="$(pkg-config --variable=prefix gmp 2>/dev/null || true)"
+  if [ -d "$libdir" ]; then
+    package_option ruby configure --with-gmp-dir="$libdir"
+  else
+    return 1
+  fi
+}
+
 use_homebrew_gmp() {
   local libdir
   libdir="$(brew --prefix gmp 2>/dev/null || true)"
@@ -1076,6 +1097,16 @@ use_freebsd_readline() {
   fi
 }
 
+use_pkgconfig_readline() {
+  local libdir
+  libdir="$(pkg-config --variable=prefix readline 2>/dev/null || true)"
+  if [ -d "$libdir" ]; then
+    package_option ruby configure --with-readline-dir="$libdir"
+  else
+    return 1
+  fi
+}
+
 use_homebrew_readline() {
   local libdir
   libdir="$(brew --prefix readline 2>/dev/null || true)"
@@ -1087,6 +1118,16 @@ use_homebrew_readline() {
   fi
 }
 
+use_pkgconfig_libffi() {
+  local libdir
+  libdir="$(pkg-config --variable=prefix libffi 2>/dev/null || true)"
+  if [ -d "$libdir" ]; then
+    package_option ruby configure --with-libffi-dir="$libdir"
+  else
+    return 1
+  fi
+}
+
 use_freebsd_libffi() {
   if is_freebsd; then
     local libffi_prefix
@@ -1114,6 +1155,14 @@ OPENSSL_VERSION_TEXT
 EOF
 }
 
+pkgconfig_openssl_version() {
+  pkg-config --modversion openssl 2>/dev/null || true
+}
+
+pkgconfig_openssl_prefix() {
+  pkg-config --variable=prefix openssl 2>/dev/null || true
+}
+
 # List all Homebrew-installed OpenSSL versions and their filesystem prefixes.
 homebrew_openssl_versions() {
   local formula version prefix
@@ -1167,6 +1216,18 @@ needs_openssl() {
   # Return early if system openssl satisfies the requirement.
   (( system_version < lower_bound || system_version >= upper_bound )) || return 1
 
+  # Look for OpenSSL using pkg-config
+  local pkgconfig_version pkgconfig_prefix
+  pkgconfig_version="$(pkgconfig_openssl_version)"
+  pkgconfig_prefix="$(pkgconfig_openssl_prefix)"
+  if [ -n "$pkgconfig_version" ] && [ -d "$pkgconfig_prefix" ]; then
+    pkgconfig_version="$(normalize_semver "$pkgconfig_version")"
+    if (( pkgconfig_version >= lower_bound && pkgconfig_version < upper_bound )); then
+      package_option ruby configure --with-openssl-dir="$pkgconfig_prefix"
+      return 1
+    fi
+  fi
+
   # Look for the latest Homebrew-installed OpenSSL that satisfies the requirement
   local brew_installs
   brew_installs="$(homebrew_openssl_versions)"