[gtkmm/gtkmm-3-24] docs/reference/Doxyfile.in: Remove PERL_PATH

[Kjell Ahlstedt <kjellahl src gnome org>]

commit d0951049839ec843beed348f6ba3ce4a4a28e818
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Mon Jun 15 17:03:41 2020 +0200

    docs/reference/Doxyfile.in: Remove PERL_PATH
    
    Doxygen since version 1.8.0 does not use PERL_PATH and MSCGEN_PATH.

 docs/reference/Doxyfile.in | 2 --
 docs/reference/meson.build | 6 ++----
 2 files changed, 2 insertions(+), 6 deletions(-)
---
diff --git a/docs/reference/Doxyfile.in b/docs/reference/Doxyfile.in
index 00d756e0..44afeabd 100644
--- a/docs/reference/Doxyfile.in
+++ b/docs/reference/Doxyfile.in
@@ -326,12 +326,10 @@ GENERATE_TAGFILE       = "reference/@GTKMM_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/docs/reference/meson.build b/docs/reference/meson.build
index 1e9a7b1e..ad863181 100644
--- a/docs/reference/meson.build
+++ b/docs/reference/meson.build
@@ -1,10 +1,9 @@
 # docs/reference
 
 # Input: built_files_root, project_source_root, gdkmm_pcname, gtkmm_pcname,
-#        perl, gdkmm_hg_ccg_basenames, gtkmm_hg_ccg_basenames,
+#        gdkmm_hg_ccg_basenames, gtkmm_hg_ccg_basenames, build_documentation,
 #        gdkmm_extra_h_files, gtkmm_extra_h_files, gdkmm_built_h_file_targets,
-#        gtkmm_built_h_file_targets, install_datadir, python3, doc_reference_py,
-#        build_documentation
+#        gtkmm_built_h_file_targets, install_datadir, python3, doc_reference_py
 # Output: install_docdir, install_devhelpdir
 
 tag_file_modules = [
@@ -64,7 +63,6 @@ doc_conf_data.set('abs_top_builddir', built_files_root)
 doc_conf_data.set('abs_top_srcdir', project_source_root)
 doc_conf_data.set('GTKMM_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',