Fix GH-17770: allow opcache.file_cache writes when JIT is enabled

[gregharmon]

Summary

zend_file_cache_script_store() had an explicit JIT guard that returned FAILURE whenever JIT_G(on) was true, which prevented second-level file cache writes under JIT.

This change removes that behavior and allows opcache.file_cache writes with JIT enabled.

Details

• ext/opcache/zend_file_cache.c
  • In zend_file_cache_script_store(), stop unconditionally failing when JIT is enabled.
  • Keep behavior safe by temporarily setting JIT_G(on)=0 during file-cache serialization/write and restoring it on all exits.
  • Re-normalize opcode handlers before serialization (ZEND_VM_SET_OPCODE_HANDLER) so runtime JIT handlers are not serialized into file cache payloads.

This preserves the intended model: file cache stores OPcache bytecode/metadata only; JIT machine code is not persisted and is rebuilt at runtime as usual.

Tests

Added regression test:

• ext/opcache/tests/gh17770_jit_file_cache_write.phpt

The test enables JIT + file cache, compiles a temp script, and asserts that at least one file is written under opcache.file_cache.

Local runs:

make test TESTS=ext/opcache/tests/gh17770_jit_file_cache_write.phpt
make test TESTS='ext/opcache/tests/gh17770_jit_file_cache_write.phpt ext/opcache/tests/gh16979_check_file_cache_function.phpt ext/opcache/tests/bug71443.phpt ext/opcache/tests/bug76275.phpt ext/opcache/tests/bug78189.phpt'

Results: new test passes; focused file-cache subset passes (with bug78189 skipped on non-Windows).

[gregharmon]

Addressed the Windows CI failure in the new GH-17770 regression test.

Update in ext/opcache/tests/gh17770_jit_file_cache_write.phpt:

• Switched opcache.file_cache to a quoted dedicated path: {PWD}/gh17770_cache
• Pre-creates that directory in --SKIPIF--
• Keeps the test hermetic by cleaning the dedicated cache directory in --CLEAN--
• Uses opcache_is_script_cached_in_file_cache() for direct script-level assertion

This keeps the regression intent unchanged while avoiding startup/path issues on Windows workers.

[dstogov]

This preserves the intended model: file cache stores OPcache bytecode/metadata only; JIT machine code is not persisted and is rebuilt at runtime as usual.

JIT compilation takes time. And it's not going to be profitable in case we re-do it on each request.
I suppose, file_cache without JIT should be faster when with JIT.

Probably, this change may be helpful for some cases - e.g rare opcache resets, but it's probably not a big problem to recompile php from sources. In case of often resets, enabling JIT will probably increase CPU load and for file_cache_only increase it significantly.