Include configuration file for all headers

Include the configuration file for all headers that were not
included, and for new headers introduced.
diff --git a/include/mbedtls/nist_kw.h b/include/mbedtls/nist_kw.h
index 5a0f656..3b67b59 100644
--- a/include/mbedtls/nist_kw.h
+++ b/include/mbedtls/nist_kw.h
@@ -37,6 +37,12 @@
 #ifndef MBEDTLS_NIST_KW_H
 #define MBEDTLS_NIST_KW_H
 
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
 #include "cipher.h"
 
 #ifdef __cplusplus