tests/tracetool: Honor the Python interpreter that "configure" detected

The tracetool tests currently fail if the host installation does not
have a "python3" binary (and you compiled QEMU by selecting a different
one during the "configure" step). This happens because tracetool-test.py
executes scripts/tracetool.py directly, so that this script is run via
its shebang line. To fix the issue, use the same Python interpreter to
run scripts/tracetool.py as we are using to run the tracetool-test.py
script.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20260115155318.37823-1-thuth@redhat.com>

tests/tracetool/tracetool-test.py

@@ -36,7 +36,8 @@ def test_tracetool_one(tracetool, backend, fmt, src_dir, build_dir):
     actual_file = Path(build_dir, rel_filename)
     expect_file = Path(src_dir, rel_filename)
 
-    args = [tracetool, f"--format={fmt}", f"--backends={backend}", "--group=testsuite"]
+    args = [sys.executable, tracetool,
+            f"--format={fmt}", f"--backends={backend}", "--group=testsuite"]
 
     if fmt.find("stap") != -1:
         args += ["--binary=qemu", "--probe-prefix=qemu"]