Fixes time() abstraction for custom configs

Added platform abstraction of time() to ChangeLog, version features, and fixed the build for dynamic configuration.
diff --git a/library/version_features.c b/library/version_features.c
index 1575e09..b852ca8 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -54,6 +54,9 @@
 #if defined(MBEDTLS_PLATFORM_EXIT_ALT)
     "MBEDTLS_PLATFORM_EXIT_ALT",
 #endif /* MBEDTLS_PLATFORM_EXIT_ALT */
+#if defined(MBEDTLS_PLATFORM_TIME_ALT)
+    "MBEDTLS_PLATFORM_TIME_ALT",
+#endif /* MBEDTLS_PLATFORM_TIME_ALT */
 #if defined(MBEDTLS_PLATFORM_FPRINTF_ALT)
     "MBEDTLS_PLATFORM_FPRINTF_ALT",
 #endif /* MBEDTLS_PLATFORM_FPRINTF_ALT */