filepath: do not run TestEvalSymlinks on Windows
filepath: do not run TestEvalSymlinks on Windows

R=golang-dev, rsc1
CC=adg, golang-dev
http://codereview.appspot.com/4274069

gnanderson/go,gnanderson/go,apparentlymart/golang,tv42/old-go,dsriram/golang,pombredanne/go-deleteme,apparentlymart/golang,ssrl/go,gnanderson/go,tv42/old-go,tv42/old-go,dsriram/golang,tv42/old-go,ssrl/go,apparentlymart/golang,pombredanne/go-deleteme,ssrl/go,ssrl/go,gnanderson/go,apparentlymart/golang,gnanderson/go,ssrl/go,dsriram/golang,tv42/old-go,apparentlymart/golang,ssrl/go,gnanderson/go,apparentlymart/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,dsriram/golang,ssrl/go,dsriram/golang,dsriram/golang,pombredanne/go-deleteme,gnanderson/go,pombredanne/go-deleteme,apparentlymart/golang,dsriram/golang,tv42/old-go,pombredanne/go-deleteme,tv42/old-go