feat: add c3 (#7891)

runtime/queries/c3/folds.scm

@@ -0,0 +1,35 @@
+[
+  ; Top-level declarations
+  (bitstruct_declaration)
+  (enum_declaration)
+  (faultdef_declaration)
+  (func_definition)
+  (import_declaration)+
+  (interface_declaration)
+  (macro_declaration)
+  (struct_declaration)
+  ; Statements
+  (asm_block_stmt)
+  (case_stmt)
+  (defer_stmt)
+  (do_stmt)
+  (for_stmt)
+  (foreach_stmt)
+  (if_stmt)
+  (switch_stmt)
+  (while_stmt)
+  (ct_for_stmt)
+  (ct_foreach_stmt)
+  (ct_switch_stmt)
+  (ct_case_stmt)
+  (ct_if_stmt)
+  (ct_else_stmt)
+  ; Comments
+  (block_comment)
+  (doc_comment)
+  ; Initializer list
+  (initializer_list)
+] @fold
+
+(compound_stmt
+  (compound_stmt) @fold)