Use `inline` on all namespace-scope constants defined in headers

Change-Id: Ic61f8d26f59fdc2895415ca47065c02d6eec28ed
diff --git a/tests/daemon/common/config-file.t.cpp b/tests/daemon/common/config-file.t.cpp
index 79c8e08..6616d3c 100644
--- a/tests/daemon/common/config-file.t.cpp
+++ b/tests/daemon/common/config-file.t.cpp
@@ -35,7 +35,7 @@
 
 BOOST_AUTO_TEST_SUITE(TestConfigFile)
 
-static const std::string CONFIG = R"CONFIG(
+const std::string CONFIG = R"CONFIG(
   a
   {
     akey avalue
@@ -47,8 +47,8 @@
 )CONFIG";
 
 // counts of the respective section counts in config_example.info
-const int CONFIG_N_A_SECTIONS = 1;
-const int CONFIG_N_B_SECTIONS = 1;
+constexpr int CONFIG_N_A_SECTIONS = 1;
+constexpr int CONFIG_N_B_SECTIONS = 1;
 
 class DummySubscriber
 {