pkg/path: enable tests on Windows

Fixes #1107.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4374041

src/pkg/Makefile

@@ -209,7 +209,6 @@ endif
 # Disable tests that windows cannot run yet.
 ifeq ($(GOOS),windows)
 NOTEST+=os/signal    # no signals
-NOTEST+=path         # tree walking does not work
 NOTEST+=syslog       # no network
 NOTEST+=time         # no syscall.Kill, syscall.SIGCHLD for sleep tests
 endif