add /opt/local/share/xsl/docbook-xsl-nons to the places to look for...

add /opt/local/share/xsl/docbook-xsl-nons to the places to look for manpages/docbook.xsl under macports

(cherry picked from commit 74252522)
15 jobs for 453-master-build-broken-in-documentation-tree-v9_11 in 13 minutes and 25 seconds (queued for 18 seconds)
Status Job ID Name Coverage
  Precheck
passed precheck:debian:sid:amd64 #30750
amd64 docker linux

00:00:15

 
  Build
passed build:centos:centos6:amd64 #30751
amd64 docker linux

00:02:17

passed build:centos:centos7:amd64 #30752
amd64 docker linux

00:02:28

passed build:debian:sid:amd64 #30753
amd64 docker linux

00:01:39

passed build:debian:sid:i386 #30754
i386 docker linux

00:01:43

 
  Test
passed systemtest:centos:centos6:amd64 #30778
linux docker amd64

00:04:17

passed systemtest:centos:centos7:amd64 #30760
amd64 docker linux

00:04:52

passed systemtest:debian:sid:amd64 #30761
amd64 docker linux

00:04:56

passed systemtest:debian:sid:i386 #30777
linux docker i386

00:04:35

passed unittest:centos:centos6:amd64 #30755
amd64 docker linux

00:00:53

passed unittest:centos:centos7:amd64 #30756
amd64 docker linux

00:01:00

passed unittest:debian:sid:amd64 #30757
amd64 docker linux

00:01:01

passed unittest:debian:sid:i386 #30758
i386 docker linux

00:00:48

failed systemtest:centos:centos6:amd64 #30759
amd64 docker linux

00:05:14

failed systemtest:debian:sid:i386 #30762
i386 docker linux

00:05:31