tool test: TestPython

[xushiwei]

No description provided.

[fennoai]

Review summary

This PR adds a TestPython golden-file test case (Python 3.14.8 bindings) under tool/_testc/python-3.14.8/, and refactors debug flag handling in tool/gen_test.go by moving cl.SetDebug/tool.SetDebug out of init() and into TestClang with a deferred reset.

Overall: The change is well-scoped and test-only. The SetDebug relocation is a clean isolation improvement (tests run sequentially, no t.Parallel(), so the deferred reset reliably restores state). One golden fixture appears not to compile — flagged inline.

Notes (non-blocking):

• Debug scope change: Previously init() enabled DbgFlagAll for every test in the package. Now only TestClang runs with debug on; TestSingleC, TestPython, and the LLVM/_testcpp tests run with it off. Since debugSettings only gates log.Println diagnostics, this is a cosmetic change and looks intentional — just confirming the intent.
• macOS-only validation: TestPython uses the full-package path (testFromDir(..., false)), which early-returns on non-darwin (only test on macOS). The committed golden files (including pyconfig.go's macOS-specific values like HAVE_KQUEUE, WITH_DYLD, X_PYTHONFRAMEWORK = "Python") are therefore only verified on macOS runners. This is consistent with the existing suite pattern, but it means the pythread.go issue below is not caught by non-darwin CI.

[fennoai]

[P2] Generated pythread.go references c1/pthread but imports neither

The golden file imports only the unaliased c package (import "github.com/goplus/lib/c"), and uses it correctly at PyLockStatus c.Uint. However, the X_PyTssT struct body references c1.Int and pthread.Key, neither of which is imported in this file:

type X_PyTssT struct {
	X_isInitialized c1.Int      // c1 undefined here
	X_key           pthread.Key // pthread undefined here
}

As written this file cannot compile (undefined: c1, undefined: pthread, and c imported but unused — the c.Uint use alone doesn't change that both other identifiers are undefined). The sibling cpython-pythread.go in the same package shows the intended import block: c1 "github.com/goplus/lib/c" (aliased) plus "github.com/goplus/lib/c/pthread". Since this is DO NOT EDIT generated output, the mismatch points to a generator import-collection bug for this file — the body emits aliased/qualified names (c1, pthread) while the import writer emitted a plain unaliased c. Recommend regenerating and confirming the import block matches the referenced identifiers rather than hand-editing the golden file.