Add -Wmissing-declarations to the SelfTest project

This required some clean-up in our test files

projects/SelfTest/IntrospectiveTests/PartTracker.tests.cpp

@@ -21,24 +21,17 @@ namespace Catch
 
 } // namespace Catch
 
-inline Catch::TrackerContext& C_A_T_C_H_Context() {
-    return Catch::TrackerContext::instance();
-}
-
 // -------------------
 
 #include "catch.hpp"
 
 using namespace Catch;
 
-//inline void testCase( Catch::LocalContext const& C_A_T_C_H_Context ) {
-//
-//    REQUIRE( C_A_T_C_H_Context().i() == 42 );
-//}
-
+namespace {
 Catch::TestCaseTracking::NameAndLocation makeNAL( std::string const& name ) {
     return Catch::TestCaseTracking::NameAndLocation( name, Catch::SourceLineInfo("",0) );
 }
+}
 
 TEST_CASE( "Tracker" ) {
 

projects/SelfTest/IntrospectiveTests/String.tests.cpp

@@ -16,23 +16,22 @@ namespace Catch {
         }
     };
 
+
+    namespace {
     auto isOwned( StringRef const& stringRef ) -> bool {
         return StringRefTestAccess::isOwned( stringRef );
     }
     auto isSubstring( StringRef const& stringRef ) -> bool {
         return StringRefTestAccess::isSubstring( stringRef );
     }
-} // namespace Catch2
+    } // end anonymous namespace
 
-namespace Catch {
-    inline auto toString( Catch::StringRef const& stringRef ) -> std::string {
-        return std::string( stringRef.currentData(), stringRef.size() );
-    }
 } // namespace Catch
 
 TEST_CASE( "StringRef", "[Strings][StringRef]" ) {
 
     using Catch::StringRef;
+    using Catch::isOwned; using Catch::isSubstring;
 
     SECTION( "Empty string" ) {
         StringRef empty;