undefined reference to `i2cWriteByteData'

[Olivier SCHMITT]

Same problem as:
folkhack/adxl345spi@93c8b0a

new make file:

LDFLAGS=-lpigpio
CFLAGS=-Wall
CC=gcc
LIBS = -L /usr/local/include -lpigpio -lrt

all:
        $(CC) $(CFLAGS) test.c $(LIBS) -o test

clean:
        rm -f test