Add build option to disable daemon control via IPC

Added a build option (nlmode) to disable the attention handler runtime
control support (IPC). Until the IPC based start/stop controls are
working correctly the build will default to nlmode enabled. The
attention handler can still be stopped and started via normal systemctl
methods.

Signed-off-by: Ben Tyner <ben.tyner@ibm.com>
Change-Id: I8913fb441fd696d81ffc04b464601238068c3131
diff --git a/meson.build b/meson.build
index ef2b206..32f2201 100644
--- a/meson.build
+++ b/meson.build
@@ -18,10 +18,18 @@
 pthread = declare_dependency(link_args : '-pthread')
 lrt = declare_dependency(link_args : '-lrt')
 
-executable('openpower-hw-diags', 'main.cpp', 'cli.cpp', 'listener.cpp',
-            dependencies : [lrt, pthread],
-            link_with : [analyzer, attn],
-            install : true)
+no_listener_mode = get_option('nlmode')
+
+if not no_listener_mode.disabled()
+  executable('openpower-hw-diags', 'main_nl.cpp', 'cli.cpp',
+              link_with : [analyzer, attn],
+              install : true)
+else
+  executable('openpower-hw-diags', 'main.cpp', 'cli.cpp', 'listener.cpp',
+              dependencies : [lrt, pthread],
+              link_with : [analyzer, attn],
+              install : true)
+endif
 
 build_tests = get_option('tests')