Take devnull's advice and write a Makefile, then all you'll have to do is type:
make
Here is a quick hint at the sort of thing you'll need:
INCLUDES=/usr/local/include
LDIRS=/usr/local/Cellar/libusb/1.0.9/lib
LIBS=usb-1.0
CC=gcc
all: xout
xout: usbtest.c
$(CC) -L $(LDIRS) -I $(INCLUDES) -o xout usbtest.c -l $(LIBS)