build: fix -Wmissing-variable-declarations

This helps make the author's original intent clear.  Tested by building
and running the unit tests with clang.

Change-Id: Iaf0aca72b5a8cc931bcb84c27df1c55d2f438dda
Signed-off-by: Brad Bishop <bradbish@qti.qualcomm.com>
diff --git a/src/main.cpp b/src/main.cpp
index 3bd529a..16493b1 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -20,7 +20,7 @@
 #include <string_view>
 #include <utility>
 
-AssociationMaps associationMaps;
+static AssociationMaps associationMaps;
 
 void updateOwners(sdbusplus::asio::connection* conn,
                   boost::container::flat_map<std::string, std::string>& owners,