Remove autodep.mk, it's not being used.

Author: graydon

Makefile.in

@@ -467,7 +467,6 @@ include $(CFG_SRC_DIR)mk/host.mk
 include $(CFG_SRC_DIR)mk/stage0.mk
 include $(CFG_SRC_DIR)mk/rt.mk
 include $(CFG_SRC_DIR)mk/rustllvm.mk
-include $(CFG_SRC_DIR)mk/autodep.mk
 include $(CFG_SRC_DIR)mk/tools.mk
 include $(CFG_SRC_DIR)mk/docs.mk
 include $(CFG_SRC_DIR)mk/llvm.mk