patch 8.2.0296: mixing up "long long" and __int64 may cause problems

Problem:    Mixing up "long long" and __int64 may cause problems. (John
            Marriott)
Solution:   Pass varnumber_T to vim_snprintf().  Add v:numbersize.
diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index 5362755..b691192 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -228,3 +228,9 @@
     call assert_fails('execute test_null_channel()', 'E908:')
   endif
 endfunc
+
+func Test_numbersize()
+  " This will fail on systems without 64 bit int support or when not configured
+  " correctly.
+  call assert_equal(64, v:numbersize)
+endfunc