Fix test_capi.test_misc when run with -R:: (#107566)

Should fix the buildbot failures.

This creates a new function each time that test is run, like Victor did for other tests.

Lib/test/test_capi/test_misc.py

@@ -2464,6 +2464,8 @@ def testfunc(x):
 
     def test_extended_arg(self):
         "Check EXTENDED_ARG handling in superblock creation"
+        ns = {}
+        exec(textwrap.dedent("""
             def many_vars():
                 # 260 vars, so z9 should have index 259
                 a0 = a1 = a2 = a3 = a4 = a5 = a6 = a7 = a8 = a9 = 42
@@ -2494,6 +2496,8 @@ def many_vars():
                 z0 = z1 = z2 = z3 = z4 = z5 = z6 = z7 = z8 = z9 = 42
                 while z9 > 0:
                     z9 = z9 - 1
+        """), ns, ns)
+        many_vars = ns["many_vars"]
 
         opt = _testinternalcapi.get_uop_optimizer()
         with temporary_optimizer(opt):