Add attention handler systemd unit file

Moved attn_handler.service file out of recipe and into
local repository and installing it via local meson.build.

Signed-off-by: Ben Tyner <ben.tyner@ibm.com>
Change-Id: Ib2f2d03ce683d65d1211777d1c162d86f9cd0ad3
diff --git a/attn/meson.build b/attn/meson.build
index 5419c7a..c715dce 100644
--- a/attn/meson.build
+++ b/attn/meson.build
@@ -19,6 +19,15 @@
 whole_archive = declare_dependency(link_args : '-Wl,--whole-archive')
 no_whole_archive = declare_dependency(link_args : '-Wl,--no-whole-archive')
 
+# install systemd unit file
+configure_file(
+    input: 'attn_handler.service',
+    output: 'attn_handler.service',
+    copy: true,
+    install_dir:
+        dependency('systemd').get_pkgconfig_variable(
+            'systemdsystemunitdir')
+)
 executable('attn_handler',
            'attn_main.cpp', 'attn_handler.cpp', 'attn_monitor.cpp',
            dependencies : [whole_archive, libpdbg,