Added the stack object to the dependencies.

makefile

@@ -4,7 +4,10 @@ SRC = ${SRC_DIR}/tty-solitaire.c
 CFLAGS = -W -Wall -pedantic -ansi -std=c99
 OUTPUT = bin/tty-solitaire
 LIB_DIR = lib
-OBJECTS = ${LIB_DIR}/frame.o ${LIB_DIR}/card.o ${LIB_DIR}/display.o
+OBJECTS = ${LIB_DIR}/frame.o   \
+          ${LIB_DIR}/card.o    \
+          ${LIB_DIR}/stack.o   \
+          ${LIB_DIR}/display.o
 LDFLAGS = -lncurses
 
 tty-solitaire: ${OBJECTS}