Disable some clang-tidy warnings in test code

The test use somewhat hacky dependency injection, so the current code is
okay here.

Author: joto

test/t/util/test_config.cpp

@@ -7,10 +7,10 @@ namespace osmium {
 
     namespace detail {
 
-        static const char* env = nullptr; // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
-        static std::string name; // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
-
+        static const char* env = nullptr; // NOLINT(cppcoreguidelines-avoid-non-const-global-variables,misc-use-anonymous-namespace)
+        static std::string name; // NOLINT(cppcoreguidelines-avoid-non-const-global-variables,misc-use-anonymous-namespace)
 
+        // NOLINTNEXTLINE(misc-use-internal-linkage)
         inline const char* getenv_wrapper(const char* var) noexcept {
             name = var;
             return env;