Makefile: fix cross compiler toolchain directory

Signed-off-by: zwliew <zhaoweiliew@gmail.com>
defconfig: enable and whole bunch of TCP congestion avoidance algorithms and set westwood as default

According to Franco's tests:

Latency - Download - Upload

cubic:
1st run: 15ms - 10,75Mbps - 7,82Mbps
2nd run: 14ms - 10,84Mbps - 8,06Mbps

reno:
1st run: 13ms - 15,51Mbps - 6,73Mbps
2nd run: 13ms - 14,73Mbps - 8,51Mbps

bic:
1st run: 12ms - 10,38Mbps - 8,61Mbps
2nd run: 13ms - 10,78Mbps - 8,62Mbps

westwood:
1st run: 11ms - 17,65Mbps - 8,30Mbps
2nd run: 13ms - 13,28Mbps - 8,29Mbps

highspeed:
1st run: 13ms - 10,76Mbps - 7,94Mbps
2nd run: 16ms - 14,42Mbps - 8,52Mbps

hybla:
1st run: 14ms - 11,19Mbps - 7,44Mbps
2nd run: 14ms - 13,47Mbps - 7,56Mbps

htcp:
1st run: 14ms - 13,24Mbps - 7,03Mbps
2nd run: 15ms - 10,85Mbps - 8,00Mbps

vegas:
1st run: 14ms - 8,49Mbps - 6,62Mbps
2nd run: 14ms - 12,00Mbps - 7,07Mbps

veno:
1st run: 13ms - 9,58Mbps - 8,13Mbps
2nd run: 13ms - 8,50Mbps - 7,64Mbps

scalable:
1st run: 18ms - 12,01Mbps - 8,73Mbps
2nd run: 14ms - 13,96Mbps - 8,23Mbps

lp:
1st run: 14ms - 14,90Mbps - 8,68Mbps
2nd run: 14ms - 13,44Mbps - 8,72Mbps

yeah:
1st run: 14ms - 13,37Mbps - 8,28Mbps
2nd run: 17ms - 13,89Mbps - 8,14Mbps

illinois:
1st run: 13ms - 12,93Mbps - 8,24Mbps
2nd run: 16ms - 13,97Mbps - 6,46Mbps

westwood algorithm provides generally the best results in terms of latency, download speed and upload speed.

Signed-off-by: zwliew <zhaoweiliew@gmail.com>