build: use full path when compiling libraries
build: use full path when compiling libraries

Makes gdb display full paths in backtrace.
Dropped during the most recent reorg.

R=r
CC=golang-dev
http://codereview.appspot.com/2216047

tav/go,tav/go,tav/go,tav/go,tav/go,tav/go,tav/go