meson: Autodetect whether autosuspend rules are provided by udev

Upstream systemd/udev is pulling our autosuspend hwdb, so if udev is new
enough, then there is no need to install the file. As such, add
auto-detection logic for the scenario.

This also changes the name of the option and the type to "feature".

data/meson.build

@@ -1,4 +1,4 @@
-if get_option('udev_rules')
+if udev_hwdb_dir != ''
     # This file has to be updated using
     # ninja -C <builddir> libfprint/sync-udev-hwdb
     # Note that the unsupported device list needs to be manually synced from

meson.build

@@ -212,15 +212,27 @@ drivers_type_func += '}'
 
 root_inc = include_directories('.')
 
-if get_option('udev_rules')
+udev_hwdb = get_option('udev_hwdb')
+if not udev_hwdb.disabled()
+    # systemd v248 includes our autosuspend rules
+    udev_versioned_dep = dependency('udev', version: '>= 248', required: false)
     udev_hwdb_dir = get_option('udev_hwdb_dir')
+    if udev_hwdb.auto()
+        if udev_versioned_dep.found()
+            udev_hwdb_dir = ''
+        endif
+    else
+        if udev_versioned_dep.found()
+            warning('udev hwdb will be installed by both systemd and libfprint')
+        endif
+    endif
 
     if udev_hwdb_dir == 'auto'
         udev_dep = dependency('udev')
         udev_hwdb_dir = udev_dep.get_pkgconfig_variable('udevdir') + '/hwdb.d'
     endif
 else
-    udev_hwdb_dir = false
+    udev_hwdb_dir = ''
 endif
 
 if get_option('gtk-examples')

meson_options.txt

@@ -6,10 +6,10 @@ option('introspection',
        description: 'Build GObject Introspection repository',
        type: 'boolean',
        value: true)
-option('udev_rules',
+option('udev_hwdb',
-       description: 'Whether to create a udev rules file',
+       description: 'Whether to create a udev hwdb',
-       type: 'boolean',
+       type: 'feature',
-       value: true)
+       value: 'auto')
 option('udev_hwdb_dir',
        description: 'Installation path for udev hwdb',
        type: 'string',