Bugs in long-literal handlin

Move n_dict to n_actions and special case n_const_list.
Generalize build_collection out of 3.7+ and into all Pythons

test/simple_source/expression/05_long_literals.py

@@ -1306,7 +1306,7 @@ assert tuple(x.keys()) == (1, 3)
 # Try a long dictionary.
 # This should not be slow as it has been in the past
 values = {
-    "valuea": a + 1,
+    "value1": x,
     "value2": 2 + 1,
     "value3": 3 + 1,
     "value4": 4 + 1,
@@ -1811,3 +1811,46 @@ values = {
 }
 
 assert list(values.values()) == list(range(2, 502 + 2))
+
+
+# Try a long dictionary that fails because we have a binary op.
+# We can get a expr32 grouping speedup
+# which is slower than if this were all constant.
+# The above was not implemented at the time this test was written.
+values = {
+    "value1": x + 1,  # This is a binary op not consant
+    "value2": 2,
+    "value3": 3,
+    "value4": 4,
+    "value5": 5,
+    "value6": 6,
+    "value7": 7,
+    "value8": 8,
+    "value9": 9,
+    "value10": 10,
+    "value11": 11,
+    "value12": 12,
+    "value13": 13,
+    "value14": 14,
+    "value15": 15,
+    "value16": 16,
+    "value17": 17,
+    "value18": 18,
+    "value19": 19,
+    "value20": 20,
+    "value21": 21,
+    "value22": 22,
+    "value23": 23,
+    "value24": 24,
+    "value25": 25,
+    "value26": 26,
+    "value27": 27,
+    "value28": 28,
+    "value29": 29,
+    "value30": 30,
+    "value31": 31,
+    "value32": 32,
+    "value33": 33,
+}
+
+assert list(values.values()) == list(range(2, 502 + 2))