[mm-common] skeletonmm: Remove PERL_PATH from Doxygen.in

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 8b19f31e63be6c4d1b7b646aa87e2feae0b1f346
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Tue Jun 2 14:44:02 2020 +0200

    skeletonmm: Remove PERL_PATH from Doxygen.in
    
    Doxygen since version 1.8.0 does not use PERL_PATH and MSCGEN_PATH.

 skeletonmm/doc/reference/Doxyfile.in | 2 --
 skeletonmm/doc/reference/meson.build | 5 ++---
 2 files changed, 2 insertions(+), 5 deletions(-)
---
diff --git a/skeletonmm/doc/reference/Doxyfile.in b/skeletonmm/doc/reference/Doxyfile.in
index 8f0147f..4b95691 100644
--- a/skeletonmm/doc/reference/Doxyfile.in
+++ b/skeletonmm/doc/reference/Doxyfile.in
@@ -311,12 +311,10 @@ GENERATE_TAGFILE       = "reference/@SKELETONMM_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/skeletonmm/doc/reference/meson.build b/skeletonmm/doc/reference/meson.build
index e1989aa..677e9ef 100644
--- a/skeletonmm/doc/reference/meson.build
+++ b/skeletonmm/doc/reference/meson.build
@@ -1,8 +1,8 @@
 # doc/reference
 
-# Input: built_files_root, project_source_root, skeletonmm_pcname, perl,
+# Input: built_files_root, project_source_root, skeletonmm_pcname, python3,
 #        hg_ccg_basenames, extra_h_files, built_h_file_targets, install_datadir,
-#        python3
+#        doc_reference
 # Output: install_docdir, install_devhelpdir
 
 tag_file_modules = [
@@ -44,7 +44,6 @@ doc_conf_data.set('abs_top_builddir', built_files_root)
 doc_conf_data.set('abs_top_srcdir', project_source_root)
 doc_conf_data.set('SKELETONMM_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',