build: make 'udevrulesdir' and 'udevhwdbdir' as Linux-only

udev is available only on Linux, so limit their usage when the backend
is 'linux'.

This fixes the build when the backend is different than 'linux', i.e.
typically on non-Linux OSes.

meson.build

@@ -81,6 +81,18 @@ if os_backend == 'linux'
     endif
     cdata.set10('HAVE_IDEVICE', true)
   endif
+
+  udevrulesdir = get_option('udevrulesdir')
+  if udevrulesdir == 'auto'
+    udev_dep = dependency('udev', required: true)
+    udevrulesdir = udev_dep.get_variable(pkgconfig: 'udev_dir') / 'rules.d'
+  endif
+
+  udevhwdbdir = get_option('udevhwdbdir')
+  if udevhwdbdir == 'auto'
+    udev_dep = dependency('udev', required: true)
+    udevhwdbdir = udev_dep.get_variable(pkgconfig: 'udev_dir') / 'hwdb.d'
+  endif
 endif
 
 historydir = get_option('historydir')
@@ -88,18 +100,6 @@ if historydir == ''
     historydir = get_option('prefix') / get_option('localstatedir') / 'lib' / 'upower'
 endif
 
-udevrulesdir = get_option('udevrulesdir')
-if udevrulesdir == 'auto'
-    udev_dep = dependency('udev', required: true)
-    udevrulesdir = udev_dep.get_variable(pkgconfig: 'udev_dir') / 'rules.d'
-endif
-
-udevhwdbdir = get_option('udevhwdbdir')
-if udevhwdbdir == 'auto'
-    udev_dep = dependency('udev', required: true)
-    udevhwdbdir = udev_dep.get_variable(pkgconfig: 'udev_dir') / 'hwdb.d'
-endif
-
 dbusdir = get_option('datadir') / 'dbus-1'
 systemdsystemunitdir = get_option('systemdsystemunitdir')
 if systemdsystemunitdir == ''

rules/meson.build

@@ -7,12 +7,14 @@ hwdb = [
     '95-upower-hid.hwdb',
 ]
 
-install_data(
-    rules,
-    install_dir: udevrulesdir,
-)
+if os_backend == 'linux'
+    install_data(
+        rules,
+        install_dir: udevrulesdir,
+    )
 
-install_data(
-    hwdb,
-    install_dir: udevhwdbdir,
-)
+    install_data(
+        hwdb,
+        install_dir: udevhwdbdir,
+    )
+endif