patch 8.1.1159: MS-Windows: with a silent (un)install $VIM/_vimrc is removed

Problem:    MS-Windows: with a silent (un)install $VIM/_vimrc is removed.
Solution:   Don't delete _vimrc in silent mode. (Ken Takata, closes #4242)

nsis/gvim.nsi

@@ -1096,7 +1096,9 @@ Section "un.$(str_unsection_rootdir)" id_unsection_rootdir
 	Call un.GetParent
 	Pop $0
 
+	${IfNot} ${Silent}
 	  Delete $0\_vimrc
+	${Endif}
 	RMDir $0
 SectionEnd
 

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1159,
 /**/
     1158,
 /**/