meson: Install items according to their relevance

The m4 and bash completion items are usable and relevant
depending on the host system's configuration.  So, we check for the
presence of the programs that these items depend on, and only install
them when those programs are found.

For the Valgrind suppression files, we don't install them on Windows as
Valgrind is currently not supported on Windows.

Als fix the path where the GDB helpers are installed, as the path is
incorrectly constructed.

This will fix the "install" stage when building on Visual Studio at
least as there are some post-install steps that are related to them,
which will make use of these programs.

https://bugzilla.gnome.org/show_bug.cgi?id=783270

gio/meson.build

@@ -693,13 +693,15 @@ endif
 #  subdir('fam')
 #endif
 
-install_data([
-  'completion/gapplication',
-  'completion/gdbus',
-  'completion/gsettings',
-  'completion/gresource'
-],
-install_dir: join_paths(get_option('datadir'), 'bash-completion/completions'))
+if have_bash
+  install_data([
+    'completion/gapplication',
+    'completion/gdbus',
+    'completion/gsettings',
+    'completion/gresource'
+  ],
+  install_dir: join_paths(get_option('datadir'), 'bash-completion/completions'))
+endif
 
 if enable_dtrace
   gio_dtrace_obj = dtrace_obj_gen.process('gio_probes.d')

glib/meson.build

@@ -274,6 +274,7 @@ else
 endif
 
 install_data('gtester-report', install_dir : get_option('bindir'))
+
 install_data('glib_gdb.py', install_dir : join_paths(glib_pkgdatadir, 'gdb'))
 
 gdb_conf = configuration_data()
@@ -283,7 +284,7 @@ configure_file(
   output: 'libglib-2.0.so.@0@-gdb.py'.format(library_version),
   configuration: gdb_conf,
   install: true,
-  install_dir: join_paths(get_option('datadir'), 'gdb/auto-load' + glib_libdir)
+  install_dir: join_paths(get_option('datadir'), 'gdb/auto-load' + get_option('libdir'))
 )
 
 if enable_systemtap

gobject/meson.build

@@ -102,7 +102,7 @@ configure_file(
   output: 'libgobject-2.0.so.@0@-gdb.py'.format(library_version),
   configuration: gdb_conf,
   install: true,
-  install_dir: join_paths(get_option('datadir'), 'gdb/auto-load/' + glib_libdir)
+  install_dir: join_paths(get_option('datadir'), 'gdb/auto-load/' + get_option('libdir'))
 )
 
 if enable_systemtap

meson.build

@@ -1499,6 +1499,11 @@ endif
 
 python = import('python3').find_python()
 
+# Determine which user environment-dependent files that we want to install
+have_bash = find_program('bash', required : false).found() # For completion scripts
+have_m4 = find_program('m4', required : false).found() # For m4 macros
+have_sh = find_program('sh', required : false).found() # For glib-gettextize
+
 # FIXME: defines in config.h that are not actually used anywhere
 # (we add them for now to minimise the diff)
 glib_conf.set('HAVE_DLFCN_H', 1)
@@ -1608,19 +1613,27 @@ endforeach
 
 # NOTE: We skip glib-zip.in because the filenames it assumes don't match ours
 
-# Install glib-gettextize executable
-configure_file(input : 'glib-gettextize.in',
-  install : true,
-  install_dir : 'bin',
-  output : 'glib-gettextize',
-  configuration : glib_conf)
+# Install glib-gettextize executable, if a UNIX-style shell is found
+if have_sh
+  configure_file(input : 'glib-gettextize.in',
+    install : true,
+    install_dir : 'bin',
+    output : 'glib-gettextize',
+    configuration : glib_conf)
+endif
 
-# Install m4 macros that other projects use
-install_data('m4macros/glib-2.0.m4', 'm4macros/glib-gettext.m4', 'm4macros/gsettings.m4',
-  install_dir : join_paths(get_option('datadir'), 'aclocal'))
-# Install Valgrind suppression file
-install_data('glib.supp',
-  install_dir : join_paths(get_option('datadir'), 'glib-2.0', 'valgrind'))
+if have_m4
+  # Install m4 macros that other projects use
+  install_data('m4macros/glib-2.0.m4', 'm4macros/glib-gettext.m4', 'm4macros/gsettings.m4',
+    install_dir : join_paths(get_option('datadir'), 'aclocal'))
+endif
+
+if host_system != 'windows'
+  # Install Valgrind suppression file (except on Windows,
+  # as Valgrind is currently not supported on Windows)
+  install_data('glib.supp',
+    install_dir : join_paths(get_option('datadir'), 'glib-2.0', 'valgrind'))
+endif
 
 configure_file(input : 'config.h.meson',
   output : 'config.h',