test/zdtm: remove unused compiler argument

Fixes a clang compile-time error:
"argument unused during compilation: '-c'".

Signed-off-by: Andrei Vagin <[email protected]>

Author: avagin

test/zdtm/Makefile.inc

@@ -76,7 +76,7 @@ endef
 
 %.d: %.c
 	$(E) " DEP      " $@
-	$(Q)$(CC) $(CFLAGS) $(CPPFLAGS) -MM -MP -c $< -o $@
+	$(Q)$(CC) $(CFLAGS) $(CPPFLAGS) -MM -MP $< -o $@
 
 %.o: %.c | %.d
 	$(E) " CC       " $@