meson: Add fru-device-less build configuration

Provide an option that skips building of fru-device.  fru-device remains
enabled and built by default.

Change-Id: If927861cf70aaf594844e28e993edc308138ddf2
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/service_files/meson.build b/service_files/meson.build
index 2f1932d..2c4909c 100644
--- a/service_files/meson.build
+++ b/service_files/meson.build
@@ -1,14 +1,16 @@
 unit_files = [
-    'xyz.openbmc_project.FruDevice.service',
-    'xyz.openbmc_project.EntityManager.service',
+    ['xyz.openbmc_project.FruDevice.service', 'fru-device'],
+    ['xyz.openbmc_project.EntityManager.service', ''],
 ]
 
 foreach u : unit_files
-    configure_file(
-        copy: true,
-        input: u,
-        install: true,
-        install_dir: systemd_system_unit_dir,
-        output: u,
-    )
+    if u[1] == '' or get_option(u[1])
+        configure_file(
+            copy: true,
+            input: u[0],
+            install: true,
+            install_dir: systemd_system_unit_dir,
+            output: u[0],
+        )
+    endif
 endforeach