[glibmm] Meson build: Use relative paths to untracked/

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 7cbfed147c8b41dfe549fe6929fa032da1571c3e
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Wed Feb 24 16:46:48 2021 +0100

    Meson build: Use relative paths to untracked/
    
    The paths to the source code in untracked/ shall be relative to the
    meson.build file, when library files are built from a tarball.
    With absolute paths Meson may generate too long file names.
    See gtkmm!61

 gio/giomm/meson.build   | 5 +++--
 glib/glibmm/meson.build | 7 ++++---
 2 files changed, 7 insertions(+), 5 deletions(-)
---
diff --git a/gio/giomm/meson.build b/gio/giomm/meson.build
index 133ed8c6..94b32eb3 100644
--- a/gio/giomm/meson.build
+++ b/gio/giomm/meson.build
@@ -212,6 +212,7 @@ install_headers('..' / 'giomm.h', subdir: giomm_pcname)
 install_headers(giomm_extra_h_files, subdir: giomm_pcname / 'giomm')
 
 untracked_giomm = 'untracked' / 'gio' / 'giomm'
+rel_untracked_giomm = '..' / '..' / untracked_giomm
 src_untracked_giomm = project_source_root / untracked_giomm
 
 extra_giomm_objects = []
@@ -346,9 +347,9 @@ else # not maintainer_mode
     giomm_hg_ccg_basenames,
   )
 
-  built_cc_files = [ src_untracked_giomm / 'wrap_init.cc' ]
+  built_cc_files = [ rel_untracked_giomm / 'wrap_init.cc' ]
   foreach file : giomm_used_hg_ccg_basenames
-    built_cc_files += src_untracked_giomm / file + '.cc'
+    built_cc_files += rel_untracked_giomm / file + '.cc'
   endforeach
 
   extra_include_dirs = [ '..', '..' / '..' / 'untracked' / 'gio',
diff --git a/glib/glibmm/meson.build b/glib/glibmm/meson.build
index ba3bb0ed..4bd78c9e 100644
--- a/glib/glibmm/meson.build
+++ b/glib/glibmm/meson.build
@@ -129,6 +129,7 @@ install_headers(glibmm_extra_h_files, subdir: glibmm_pcname / 'glibmm')
 install_headers(glibmm_extra_ph_files, subdir: glibmm_pcname / 'glibmm' / 'private')
 
 untracked_glibmm = 'untracked' / 'glib' / 'glibmm'
+rel_untracked_glibmm = '..' / '..' / untracked_glibmm
 src_untracked_glibmm = project_source_root / untracked_glibmm
 
 extra_glibmm_objects = []
@@ -286,12 +287,12 @@ else # not maintainer_mode
     glibmm_h_m4_files + glibmm_cc_m4_files,
   )
 
-  built_cc_files = [ src_untracked_glibmm / 'wrap_init.cc' ]
+  built_cc_files = [ rel_untracked_glibmm / 'wrap_init.cc' ]
   foreach file : glibmm_hg_ccg_basenames
-    built_cc_files += src_untracked_glibmm / file + '.cc'
+    built_cc_files += rel_untracked_glibmm / file + '.cc'
   endforeach
   foreach file : glibmm_cc_m4_files
-    built_cc_files += src_untracked_glibmm / file
+    built_cc_files += rel_untracked_glibmm / file
   endforeach
 
   extra_include_dirs = [ '..', '..' / '..' / 'untracked' / 'glib' ]