Revert "Make clang_ast_t.ml* non recursive"

Summary:
that commit broke build because of
'unused rec flag' warning.
Looks like atdgen code generation is at fault

infer/src/Makefile

@@ -176,10 +176,10 @@ $(INFERPRINT_ATDGEN_STUBS): $(INFERPRINT_ATDGEN_STUB_ATD)
 $(CLANG_ATDGEN_STUBS) $(INFER_CLANG_AST_PROJ): $(CLANG_ATDGEN_STUB_ATD) $(CLANG_PLUGIN_BINARIES) $(FCP_CLANG_AST_PROJ) $(FCP_CLANG_AST_MAIN)
 # rebuild the artifacts of the AST files whenever they're upated in FCP
 # also copy the ast_proj files whenever they are updated
-	$(ATDGEN) -t $(CLANG_ATDGEN_STUB_ATD) -o $(CLANG_ATDGEN_STUB_BASE)
+	$(ATDGEN) -rec -t $(CLANG_ATDGEN_STUB_ATD) -o $(CLANG_ATDGEN_STUB_BASE)
-	$(ATDGEN) -b $(CLANG_ATDGEN_STUB_ATD) -o $(CLANG_ATDGEN_STUB_BASE)
+	$(ATDGEN) -rec -b $(CLANG_ATDGEN_STUB_ATD) -o $(CLANG_ATDGEN_STUB_BASE)
-	$(ATDGEN) -j $(CLANG_ATDGEN_STUB_ATD) -o $(CLANG_ATDGEN_STUB_BASE)
+	$(ATDGEN) -rec -j $(CLANG_ATDGEN_STUB_ATD) -o $(CLANG_ATDGEN_STUB_BASE)
-	$(ATDGEN) -v $(CLANG_ATDGEN_STUB_ATD) -o $(CLANG_ATDGEN_STUB_BASE)
+	$(ATDGEN) -rec -v $(CLANG_ATDGEN_STUB_ATD) -o $(CLANG_ATDGEN_STUB_BASE)
 	$(COPY) $(CLANG_OCAML_BUILD)/clang_ast_proj.ml $(CLANG_SOURCES)
 	$(COPY) $(CLANG_OCAML_BUILD)/clang_ast_proj.mli $(CLANG_SOURCES)
 	$(COPY) $(CLANG_OCAML_ROOT)/clang_ast_visit.ml $(CLANG_SOURCES)