Teach CompHash to allow indexing by records with vector/table/set fields.

Addresses #464.

testing/btest/Baseline/language.record-index-complex-fields/output

@@ -0,0 +1,27 @@
+{
+[1.2.3.4] = {
+[a=4, tags_v=[0, 1], tags_t={
+[two] = 2,
+[one] = 1
+}, tags_s={
+b,
+a
+}]
+}
+}
+{
+[a=13, tags_v=[, , 2, 3], tags_t={
+[four] = 4,
+[five] = 5
+}, tags_s={
+d,
+c
+}],
+[a=4, tags_v=[0, 1], tags_t={
+[two] = 2,
+[one] = 1
+}, tags_s={
+b,
+a
+}]
+}