patch 8.2.2388: no easy way to get the maximum or mininum number value

Problem:    No easy way to get the maximum or mininum number value.
Solution:   Add v:numbermax and v:numbermin.
diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index e5f521c..52e8df9 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -256,10 +256,13 @@
   endif
 endfunc
 
-func Test_numbersize()
-  " This will fail on systems without 64 bit int support or when not configured
-  " correctly.
+func Test_number_max_min_size()
+  " This will fail on systems without 64 bit number support or when not
+  " configured correctly.
   call assert_equal(64, v:numbersize)
+
+  call assert_true(v:numbermin < -9999999)
+  call assert_true(v:numbermax > 9999999)
 endfunc
 
 func Assert_reg(name, type, value, valuestr, expr, exprstr)