[atkmm] doc/reference/: Update for Doxygen >= 1.8.16

[Kjell Ahlstedt <kjellahl src gnome org>]

commit a2779474dce7216ad68dfab04ceeaa80ea3c3a9c
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Mon Jun 29 16:46:30 2020 +0200

    doc/reference/: Update for Doxygen >= 1.8.16
    
    * doc/reference/meson.build: Doxygen 1.8.16 and later does not store
    tag file names in the html files. This requires changes in meson.build
    and in doc-install.pl (in mm-common). Otherwise references to other modules
    won't be updated in the html files when they are installed.
    * doc/reference/Doxyfile.in: Remove PERL_PATH and MSCGEN_PATH.
    Doxygen since version 1.8.0 does not use them.

 doc/reference/Doxyfile.in |  2 --
 doc/reference/meson.build | 16 +++++++++-------
 2 files changed, 9 insertions(+), 9 deletions(-)
---
diff --git a/doc/reference/Doxyfile.in b/doc/reference/Doxyfile.in
index 0bff6f0..276adb3 100644
--- a/doc/reference/Doxyfile.in
+++ b/doc/reference/Doxyfile.in
@@ -310,12 +310,10 @@ GENERATE_TAGFILE       = "reference/@ATKMM_MODULE_NAME@.tag"
 ALLEXTERNALS           = NO
 EXTERNAL_GROUPS        = NO
 EXTERNAL_PAGES         = YES
-PERL_PATH              = @PERL@
 #---------------------------------------------------------------------------
 # Configuration options related to the dot tool
 #---------------------------------------------------------------------------
 CLASS_DIAGRAMS         = YES
-MSCGEN_PATH            =
 DIA_PATH               =
 HIDE_UNDOC_RELATIONS   = NO
 HAVE_DOT               = YES
diff --git a/doc/reference/meson.build b/doc/reference/meson.build
index 404c77d..fb913a0 100644
--- a/doc/reference/meson.build
+++ b/doc/reference/meson.build
@@ -1,8 +1,8 @@
 # doc/reference
 
-# Input: built_files_root, project_source_root, atkmm_pcname, perl,
-#        hg_ccg_basenames, extra_h_files, built_h_file_targets, install_datadir,
-#        python3, doc_reference_py
+# Input: built_files_root, project_source_root, atkmm_pcname, hg_ccg_basenames,
+#        extra_h_files, built_h_file_targets, install_datadir, python3,
+#        doc_reference_py
 # Output: install_docdir, install_devhelpdir
 
 tag_file_modules = [
@@ -24,10 +24,13 @@ foreach module : tag_file_modules
       htmlrefdir = htmlrefpub
     endif
     doxygen_tagfiles += ' "' + doxytagfile + '=' + htmlrefpub + '"'
-    if not htmlrefdir.endswith('/')
-      htmlrefdir += '/'
-    endif
+
+    # Doxygen <= 1.8.15
     docinstall_flags += ['-l', doxytagfile.split('/')[-1] + '@' + htmlrefdir]
+    if htmlrefpub != htmlrefdir
+      # Doxygen >= 1.8.16
+      docinstall_flags += ['-l', 's@' + htmlrefpub + '@' + htmlrefdir]
+    endif
   endif
 endforeach
 
@@ -44,7 +47,6 @@ doc_conf_data.set('abs_top_builddir', built_files_root)
 doc_conf_data.set('abs_top_srcdir', project_source_root)
 doc_conf_data.set('ATKMM_MODULE_NAME', book_name)
 doc_conf_data.set('DOXYGEN_TAGFILES', doxygen_tagfiles)
-doc_conf_data.set('PERL', perl.found() ? perl.path() : '')
 
 configure_file(
   input: 'Doxyfile.in',