add hash to build; rm pkg/* in clean.bash

R=r
DELTA=3  (3 added, 0 deleted, 0 changed)
OCL=19935
CL=19937

src/clean.bash

@@ -3,6 +3,7 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
+rm -f $GOROOT/pkg/*.[6a]
 for i in lib9 libbio libmach_amd64 libregexp cmd runtime lib
 do
 	cd $i

src/lib/Makefile

@@ -9,6 +9,7 @@ GC=6g
 DIRS=\
 	container/array\
 	fmt\
+	hash\
 	http\
 	math\
 	net\
@@ -86,6 +87,7 @@ io.6: os.dirinstall syscall.dirinstall
 testing.6: flag.install fmt.dirinstall
 
 fmt.dirinstall: io.install reflect.dirinstall strconv.dirinstall
+hash.dirinstall: os.dirinstall
 http.dirinstall: bufio.install io.install net.dirinstall os.dirinstall strings.install
 net.dirinstall: once.install os.dirinstall strconv.dirinstall
 os.dirinstall: syscall.dirinstall