patch 8.1.2226: cannot use system copy/paste in non-xterm terminals

Problem:    Cannot use system copy/paste in non-xterm terminals.
Solution:   Instead of setting 'mouse' to "a" set it to "nvi" in defaults.vim.
diff --git a/runtime/defaults.vim b/runtime/defaults.vim
index 255b67b..e7929ea 100644
--- a/runtime/defaults.vim
+++ b/runtime/defaults.vim
@@ -75,8 +75,14 @@
 
 " In many terminal emulators the mouse works just fine.  By enabling it you
 " can position the cursor, Visually select and scroll with the mouse.
+" Only xterm can grab the mouse events when using the shift key, for other
+" terminals use ":", select text and press Esc.
 if has('mouse')
-  set mouse=a
+  if &term =~ 'xterm'
+    set mouse=a
+  else
+    set mouse=nvi
+  endif
 endif
 
 " Switch syntax highlighting on when the terminal has colors or when using the