Fix copypasta in #endif comment

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/base64_invasive.h b/library/base64_invasive.h
index 9e26471..ed5f7cb 100644
--- a/library/base64_invasive.h
+++ b/library/base64_invasive.h
@@ -52,4 +52,4 @@
 signed char mbedtls_base64_dec_value( unsigned char c );
 #endif /* MBEDTLS_TEST_HOOKS */
 
-#endif /* MBEDTLS_SSL_INVASIVE_H */
+#endif /* MBEDTLS_BASE64_INVASIVE_H */