Split HAVE_TIME into HAVE_TIME + HAVE_TIME_DATE

First one means we have time() but it may not return the actual wall clock
time, second means it does.
diff --git a/library/x509.c b/library/x509.c
index 2efa62f..0ca4b4a 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -874,11 +874,7 @@
     return( 0 );
 }
 
-/*
- * Return 0 if the mbedtls_x509_time is still valid, or 1 otherwise.
- */
-#if defined(MBEDTLS_HAVE_TIME)
-
+#if defined(MBEDTLS_HAVE_TIME_DATE)
 static int x509_get_current_time( mbedtls_x509_time *now )
 {
 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
@@ -982,7 +978,7 @@
     return( x509_check_time( from, &now ) );
 }
 
-#else  /* MBEDTLS_HAVE_TIME */
+#else  /* MBEDTLS_HAVE_TIME_DATE */
 
 int mbedtls_x509_time_is_past( const mbedtls_x509_time *to )
 {
@@ -995,7 +991,7 @@
     ((void) from);
     return( 0 );
 }
-#endif /* MBEDTLS_HAVE_TIME */
+#endif /* MBEDTLS_HAVE_TIME_DATE */
 
 #if defined(MBEDTLS_SELF_TEST)