debug/gosym: avoid test failure on Windows
debug/gosym: avoid test failure on Windows

Would fix build if build hadn't already been broken with something else.

TBR=golang-dev
CC=golang-dev
https://codereview.appspot.com/11525043

pombredanne/go-deleteme,tv42/old-go,tv42/old-go,apparentlymart/golang,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,pombredanne/go-deleteme,apparentlymart/golang,apparentlymart/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,apparentlymart/golang,tv42/old-go,tv42/old-go,apparentlymart/golang,tv42/old-go,pombredanne/go-deleteme,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang