Add slightly odd signal testing + fork() example

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

examples/Makefile

@@ -24,7 +24,7 @@
 #
 .PHONY: all clean
 
-TARGET      = joystick test
+TARGET      = signal test joystick
 OBJS       := $(addsuffix .o, $(TARGET))
 SRCS       := $(OBJS:.o=.c)
 DEPS       := $(SRCS:.c=.d)
@@ -38,6 +38,8 @@ include ../rules.mk
 
 all: $(TARGET)
 
+signal: signal.o
+
 test: test.o
 
 joystick: joystick.o