Tidy up a few problems with run-make tests

Use the correct set of dependencies as well as CFG_PYTHON instead of assuming
'python' is the right one.

Author: alexcrichton

mk/tests.mk

@@ -920,11 +920,11 @@ $$(call TEST_OK_FILE,$(1),$(2),$(3),rmake): \
 
 $(3)/test/run-make/%-$(1)-T-$(2)-H-$(3).ok: \
 		$(S)src/test/run-make/%/Makefile \
-		$$(HBIN$(1)_H_$(3))/rustc$$(X_$(3))
+		$$(HSREQ$(1)_H_$(3))
 	@rm -rf $(3)/test/run-make/$$*
 	@mkdir -p $(3)/test/run-make/$$*
 	@echo maketest: $$*
-	$$(Q)python $(S)src/etc/maketest.py $$(dir $$<) \
+	$$(Q)$$(CFG_PYTHON) $(S)src/etc/maketest.py $$(dir $$<) \
 	    $$(HBIN$(1)_H_$(3))/rustc$$(X_$(3)) \
 	    $(3)/test/run-make/$$* \
 	    "$$(CC_$(3)) $$(CFG_GCCISH_CFLAGS_$(3))"