patch 8.0.0705: crash when there is an error in a timer callback

Problem:    Crash when there is an error in a timer callback. (Aron Griffis,
            Ozaki Kiichi)
Solution:   Check did_throw before discarding an exception.  NULLify
            current_exception when no longer valid.

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    705,
 /**/
     704,
 /**/