[PHP] fix: split ABI syscall and residual runtime fixes

[brandonpayton]

Summary

• split the remaining ABI/syscall/dev-shell residual fixes out of mixed PHP PHPT PR Preserve shared mappings across fork for PHP PHPTs #717
• stack on [PHP] fix: split host browser and SharedFS runtime fixes #738 via Automattic branch integration/kd-6nz-php-phpt-host-browser-base
• keep this PR in the PHP harness stack, not targeted at main

Stack

• Harness PR: [PHP] Add upstream PHPT harness #736
• Prior stack: [PHP] fix: split socket datagram and multicast semantics #734 socket/network, [PHP] fix: split fork/process/shared-memory runtime fixes #737 fork/process/shared-memory, [PHP] fix: split host browser and SharedFS runtime fixes #738 host/browser/SharedFS
• Direct base: integration/kd-6nz-php-phpt-host-browser-base

Preserved commits

• fc4f631 fix: align syscall_cp wasm32 signature
• e2d3f18 fix: patch musl syscall_cp fallback signature
• d94865c fix: provide route netlink loopback enumeration
• 3a9a0db fix: preserve offset on invalid lseek
• b0b84eb fix: interrupt select retries on caught signals
• 53ea154 fix: implement times syscall for php fpm tests
• c6a257c test: remove stale sortix pthread xfail
• 771abb8 Declare bzip2 for pure dev-shell xtask linking

Notes

• Default OpenSSL config work remains isolated in [PHP] fix: provide default openssl config file #726; it is not duplicated here.
• TCP close semantics remain isolated in [PHP] fix: split TCP close semantics stack #735 over [PHP] fix: raise SIGPIPE for bridged TCP EPIPE #729.

Verification

• git diff --check origin/integration/kd-6nz-php-phpt-host-browser-base...HEAD

[brandonpayton]

Closing as superseded by origin-headed replacement #758: #758

This PR head was in brandonpayton/kandelo-agentic-dev. The replacement uses the same head SHA (771abb8) on an Automattic/kandelo origin branch and has an expanded description explaining why the change is needed and why it belongs in Kandelo.