Use make automatic variables to install updated manuals

Make will choose modified manual from build directory or original from source
directory automagically. Take advantage of install tool feature.
Install all files in single command instead of iterating on each of them.

(cherry picked from commit 88f913ac)
13 jobs for modified-manual-install-oot-v9_11 in 7 minutes and 19 seconds (queued for 7 seconds)
Status Job ID Name Coverage
  Precheck
passed precheck:debian:sid:amd64 #29533
amd64 docker linux

00:00:13

 
  Build
passed build:centos:centos6:amd64 #29534
amd64 docker linux

00:02:21

passed build:centos:centos7:amd64 #29535
amd64 docker linux

00:02:30

passed build:debian:sid:amd64 #29536
amd64 docker linux

00:01:23

passed build:debian:sid:i386 #29537
i386 docker linux

00:01:46

 
  Test
passed systemtest:centos:centos6:amd64 #29542
docker linux amd64

00:04:27

passed systemtest:centos:centos7:amd64 #29543
amd64 docker linux

00:04:24

passed systemtest:debian:sid:amd64 #29544
amd64 docker linux

00:04:34

passed systemtest:debian:sid:i386 #29545
i386 docker linux

00:04:33

passed unittest:centos:centos6:amd64 #29538
amd64 docker linux

00:01:05

passed unittest:centos:centos7:amd64 #29539
amd64 docker linux

00:01:09

passed unittest:debian:sid:amd64 #29540
amd64 docker linux

00:00:51

passed unittest:debian:sid:i386 #29541
i386 docker linux

00:00:51