msetup: fix regression under py3.13 causing profile.runctx to not wri…

…te locals()

"PEP 667: Consistent views of namespaces" caused locals() to be
inconsistent between uses since it is now created afresh every time you
invoke it and writes to it are dropped. `sys._getframe().f_locals` is
equivalent but preserves writes (it doesn't create a new dict) and
unfortunately doesn't help at all as it's documented to be a private
implementation detail of CPython that "should be used for internal and
specialized purposes only".

Work around this by saving locals to a variable reference and both
passing it into runctx and reusing it in lookups of the result. This
works okay for both new and older versions of python.

Bug: python/cpython#115153

mesonbuild/msetup.py

@@ -242,10 +242,11 @@ def _generate(self, env: environment.Environment, capture: bool, vslite_ctx: T.O
 
             self.finalize_postconf_hooks(b, intr)
             if self.options.profile:
+                localvars = locals()
                 fname = f'profile-{intr.backend.name}-backend.log'
                 fname = os.path.join(self.build_dir, 'meson-logs', fname)
-                profile.runctx('gen_result = intr.backend.generate(capture, vslite_ctx)', globals(), locals(), filename=fname)
-                captured_compile_args = locals()['gen_result']
+                profile.runctx('gen_result = intr.backend.generate(capture, vslite_ctx)', globals(), localvars, filename=fname)
+                captured_compile_args = localvars['gen_result']
                 assert captured_compile_args is None or isinstance(captured_compile_args, dict)
             else:
                 captured_compile_args = intr.backend.generate(capture, vslite_ctx)