patch 8.0.1045: running tests may pollute shell history

Problem:    Running tests may pollute shell history. (Manuel Ortega)
Solution:   Make $HISTFILE empty.

src/testdir/setup.vim

@@ -21,6 +21,9 @@ if 1
     let $XAUTHORITY = $HOME . '/.Xauthority'
   endif
 
+  " Avoid storing shell history.
+  let $HISTFILE = ""
+
   " Make sure $HOME does not get read or written.
   " It must exist, gnome tries to create $HOME/.gnome2
   let $HOME = getcwd() . '/XfakeHOME'

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1045,
 /**/
     1044,
 /**/