unit-fail-monitor: add meson option to disable

Add an option to disable this feature.

Change-Id: Ifc953ad4bec492f7c6ca8190e4c6a0820b12630a
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meson_options.txt b/meson_options.txt
index 71f7241..bf610a6 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -4,3 +4,10 @@
     value: 'enabled',
     description: 'Build tests'
 )
+
+option(
+    'unit-failure-monitor',
+    type: 'feature',
+    value: 'enabled',
+    description: 'Build phosphor-unit-failure-monitor'
+)