tests CHANGE headers includes cleanup

Set necessary include directories instead of including library headers
in tests via relative path (which cause problems when building in
some nonstandard build directories).
diff --git a/tests/utests/schema/test_schema.h b/tests/utests/schema/test_schema.h
index b6f1929..d0212fb 100644
--- a/tests/utests/schema/test_schema.h
+++ b/tests/utests/schema/test_schema.h
@@ -14,9 +14,9 @@
 #ifndef TESTS_UTESTS_SCHEMA_TEST_SCHEMA_H_
 #define TESTS_UTESTS_SCHEMA_TEST_SCHEMA_H_
 
-#include "config.h"
 #include "log.h"
 #include "parser_schema.h"
+#include "tests/config.h"
 
 /* set to 0 to printing error messages to stderr instead of checking them in code */
 #define ENABLE_LOGGER_CHECKING 1