build: remove junk form autodependencies

-MD accepts no argument, and luckily the argument we supplied evaluated to
nothing.  Remove it.

Makefile

@@ -4,7 +4,7 @@ CFLAGS = $(autodepend) -g -Wall -Wno-pointer-arith $(INCLUDES) -Werror
 ASFLAGS = -g $(autodepend)
 
 sys-includes = $(jdkbase)/include $(jdkbase)/include/linux
-autodepend = -MD $(@.o=.d) -MT $@ -MP
+autodepend = -MD -MT $@ -MP
 
 do-sys-includes = $(foreach inc, $(sys-includes), -isystem $(inc))