stable-3.4 branch fails to find docbook XSL on Woodie

[strk]

For some reason this is now happenign on stable-3.4:

xsl style sheets:

​https://woodie.osgeo.org/repos/30/pipeline/1356/6#L300

Subsequent build of html fails:

​https://woodie.osgeo.org/repos/30/pipeline/1356/9#L8

I'm not sure since when this has been failing because the "docs" workflow is only executed when something under doc/ dir changes

The configure output doesn't show much info about what was tested but eventually warns about that:

configure: WARNING: could not locate Docbook stylesheets required to build the documentation

​https://woodie.osgeo.org/repos/30/pipeline/1356/6#L137

[Sandro Santilli <strk@…>]

In 2a2e040b/git:

Add notice message about docbook xsl lookup

References #5588

[strk]

I'm trying to build in the postgis-build-test docker container on woodie-server and the configure script there is able to find the stylesheets, but still doesn't set the appropriate variable:

checking for html/docbook.xsl in URI http://cdn.docbook.org/release/xsl/current...... not found
checking for html/docbook.xsl in URI http://docbook.sourceforge.net/release/xsl-ns/current...... found
...
 -------- Documentation Generation --------
  xsltproc:             /usr/bin/xsltproc
  xsl style sheets:
  dblatex:              /usr/bin/dblatex
  convert:              /usr/bin/convert
  mathml2.dtd:          /usr/share/xml/schema/w3c/mathml/dtd/mathml2.dtd

[Sandro Santilli <strk@…>]

In bfa43e4/git:

Add docbook-xsl-ns to search path for docbook stylesheets

Should fix #5588

[strk]

For the record: we didnt' notice before because we are ONLY building docs when docs change, and we usually only change docs in master branch while [68210b67391f0a7478313a430f0f44cdd2f74e44/git] changed docs in stable-3.4

It will take another docs modification to really confirm this bug is fixed

[Sandro Santilli <strk@…>]

In 44f4d0c/git:

Update po files

Includes Drop of file locations but buried within that (which
won't happen in the future) there's also updates after the real
update of .xml files (after update of the .pot)

This commit also serves as a test for docbook finding bug.
References #5588

[strk]

Ok the fix was really in [44f4d0c/git] and is confirmed by Woodie now: ​https://woodie.osgeo.org/repos/30/pipeline/1365/6#L139

Basically we were not looking into docbook-xsl-ns