Added exercise for signal handler

exercises/signal_handler/Makefile

@@ -0,0 +1,12 @@
+CC = gcc
+CFLAGS = -Wall -Wextra -O2
+TARGET = signal_handler
+SRC = main.c
+
+all: $(TARGET)
+
+$(TARGET): $(SRC)
+	$(CC) $(CFLAGS) -o $(TARGET) $(SRC)
+
+clean:
+	rm -f $(TARGET)