unix: remove absolute path of pwd from mkall.sh

The pwd command does not always reside under /bin for all Linux
distributions. As a $PATH is otherwise always assumed, here too.

Change-Id: I8a9b65fedc0bdd6b963f30e69d5c98b1550326cd
GitHub-Last-Rev: ff9227dbe6029506a932d033feea2059c15b4fec
GitHub-Pull-Request: golang/sys#161
Reviewed-on: https://go-review.googlesource.com/c/sys/+/500656
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/unix/mkall.sh b/unix/mkall.sh
index 8e3947c..e6f31d3 100755
--- a/unix/mkall.sh
+++ b/unix/mkall.sh
@@ -50,7 +50,7 @@
 	# Use the Docker-based build system
 	# Files generated through docker (use $cmd so you can Ctl-C the build or run)
 	$cmd docker build --tag generate:$GOOS $GOOS
-	$cmd docker run --interactive --tty --volume $(cd -- "$(dirname -- "$0")/.." && /bin/pwd):/build generate:$GOOS
+	$cmd docker run --interactive --tty --volume $(cd -- "$(dirname -- "$0")/.." && pwd):/build generate:$GOOS
 	exit
 fi