make Makefile compatible with Solaris

main/Unix/Makefile

@@ -9,14 +9,14 @@ all: cDirectory.o ipc.o set_return_code_c.o \
 	Clean\ System\ Files/set_return_code_c.o
 
 Clean\ System\ Files:
-	mkdir "Clean System Files"
+	mkdir -p "Clean System Files"
 
 Clean\ System\ Files/cDirectory.o : cDirectory.c
-	$(CC) -c $(CFLAGS) $< -o "$@"
+	$(CC) -c $(CFLAGS) cDirectory.c -o "Clean System Files/cDirectory.o"
 
 Clean\ System\ Files/ipc.o : ipc.c
-	$(CC) -c $(CFLAGS) $< -o "$@"
+	$(CC) -c $(CFLAGS) ipc.c -o "Clean System Files/ipc.o"
 
 Clean\ System\ Files/set_return_code_c.o : set_return_code_c.c
-	$(CC) -c $(CFLAGS) $< -o "$@"
+	$(CC) -c $(CFLAGS) set_return_code_c.c -o "Clean System Files/set_return_code_c.o"