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/include/mbedtls/platform.h b/include/mbedtls/platform.h
index 7922e8c..69a6afd 100644
--- a/include/mbedtls/platform.h
+++ b/include/mbedtls/platform.h
@@ -44,6 +44,7 @@
 #if !defined(MBEDTLS_PLATFORM_NO_STD_FUNCTIONS)
 #include <stdio.h>
 #include <stdlib.h>
+#include <time.h>
 #if !defined(MBEDTLS_PLATFORM_STD_SNPRINTF)
 #if defined(_WIN32)
 #define MBEDTLS_PLATFORM_STD_SNPRINTF   mbedtls_platform_win32_snprintf /**< Default snprintf to use  */
@@ -243,7 +244,7 @@
  * The function pointers for time
  */
 #if defined(MBEDTLS_PLATFORM_TIME_ALT)
-extern time_t (*mbedtls_time)( mbedtls_time_t* time );
+extern mbedtls_time_t (*mbedtls_time)( mbedtls_time_t* time );
 
 /**
  * \brief   Set your own time function pointer
@@ -252,7 +253,7 @@
  *
  * \return              0
  */
-int mbedtls_platform_set_time( mbedtls_time_t (*time_func)( mbedtls_time_t time ) );
+int mbedtls_platform_set_time( mbedtls_time_t (*time_func)( mbedtls_time_t* time ) );
 #else
 #if defined(MBEDTLS_PLATFORM_TIME_MACRO)
 #define mbedtls_time    MBEDTLS_PLATFORM_TIME_MACRO