forward-port feat/pgo fixes

Forward-port the genuinely-new fixes from feat/pgo (2026-06-09 .. 07-09)
into v3's reorganized layout:

- zig-cc.sh: prefix runtime-lib appends with `-x none` so the profile/crt/
  cpu_model archives don't poison the following files as `-x c` sources
- ZigToolchain: set ax_cv_have_func_attribute_ifunc=no under -flto
  (an ifunc in LTO bitcode crashes zig 0.16's lld during thin-link)
- php configure: add --with-sysconfdir option; strip build-time env vars
  from phpinfo's "Configure Command"
- ext-brotli / ext-zstd: switch to stable release/tag tarballs; brotli
  configures with --with-libbrotli
- ext-event: patch libevent http_connection.c to use a const peer address
  (both static and shared builds)
- ghrel downloader: prefer GitHub's /releases/latest (the semantically
  latest stable release) over publish-order iteration, so a newer-tagged
  prerelease (e.g. libevent 2.2.x-alpha) can't win over 2.1.x-stable

Commits already present in v3 were skipped: protobuf-latest + libaom
ENABLE_*=OFF (9398a667), the clang runtime -target flag (2adedc09), the
runtime-bits fail-hard half of 3823631a, and github prefer-stable's
prerelease skip (incl. the ghtar /releases/latest path, already in v3).

src/Package/Extension/event.php

@@ -35,12 +35,30 @@ class event extends PhpExtensionPackage
 
     #[BeforeStage('php', [php::class, 'makeForUnix'], 'ext-event')]
     #[PatchDescription('Prevent event extension compile error on macOS')]
+    #[PatchDescription('Patch libevent http_connection.c to use a const peer address')]
     public function patchBeforeMake(PackageInstaller $installer): void
     {
+        $php_src = $installer->getTargetPackage('php')->getSourceDir();
         // Prevent event extension compile error on macOS
         if (SystemTarget::getTargetOS() === 'Darwin') {
-            $php_src = $installer->getTargetPackage('php')->getSourceDir();
             FileSystem::replaceFileRegex("{$php_src}/main/php_config.h", '/^#define HAVE_OPENPTY 1$/m', '');
         }
+        $this->patchLibeventConstPeer("{$php_src}/ext/event");
+    }
+
+    #[BeforeStage('ext-event', [PhpExtensionPackage::class, 'makeForUnix'])]
+    #[PatchDescription('Patch libevent http_connection.c to use a const peer address')]
+    public function patchBeforeSharedMake(PhpExtensionPackage $pkg): void
+    {
+        $this->patchLibeventConstPeer($pkg->getSourceDir());
+    }
+
+    private function patchLibeventConstPeer(string $event_source_dir): bool
+    {
+        $file = "{$event_source_dir}/php8/classes/http_connection.c";
+        if (is_file($file) && FileSystem::replaceFileRegex($file, '/^\tchar \*address;$/m', "\tconst char *address;")) {
+            return true;
+        }
+        return false;
     }
 }