Attention Handler base logic

Added base logic for the attention handler application (attn) as a starting point for further refinement. Attn will handle SBE vital, system checkstop and special attention events. These events will be handled through a combination local logic and external hardware and software interfaces.

Signed-off-by: Ben Tyner <ben.tyner@ibm.com>
Change-Id: I074fb86474761bf694644c71d93ede9c45673b79
diff --git a/meson.build b/meson.build
index b28887d..9dc0caa 100644
--- a/meson.build
+++ b/meson.build
@@ -7,6 +7,7 @@
         ])
 
 subdir('src')
+subdir('attn')
 
 build_tests = get_option('tests')