Here is a Makefile for the monte_pi_sprng.c program:

# Makefile to build monte_pi_sprng program
# --- macros
CC=cc
CFLAGS=  -O3 -I /usr/local/lib/sprng/include -I /usr/local/lib/pgplot -g
OBJECTS= monte_pi_sprng.o plot.o
LIBS = -L/usr/local/lib/sprng/lib -llcg -L/usr/local/lib/pgplot -lcpgplot -lpgplot -lX11 -lftn -lm


# --- targets
all:    monte_pi_sprng
monte_pi_sprng:   $(OBJECTS) 
       $(CC)  -o monte_pi_sprng  $(OBJECTS) $(LIBS)
        
monte_pi_sprng.o: /usr/local/lib/sprng/include/sprng.h /usr/local/lib/pgplot/cpgplot.h monte_pi_sprng.c
       $(CC) $(CFLAGS) -c monte_pi_sprng.c
       
plot.o: /usr/local/lib/pgplot/cpgplot.h plot.c
       $(CC) $(CFLAGS) -c plot.c 


# --- remove binary and executable files
clean:
       rm -f monte_pi_sprng $(OBJECTS)

        

Notes about this Makefile:

Issue the command 'make all' or 'make monte_pi_sprng' to build the program.
Issue the command 'make clean' to rebuild the entire application