patch 8.2.4893: distributed import files are not installed

Problem:    Distributed import files are not installed.
Solution:   Add rules to Makefile and NSIS.
diff --git a/nsis/gvim.nsi b/nsis/gvim.nsi
index f9b1790..d71cffb 100644
--- a/nsis/gvim.nsi
+++ b/nsis/gvim.nsi
@@ -403,6 +403,9 @@
 	SetOutPath $0\autoload\xml
 	File ${VIMRT}\autoload\xml\*.*
 
+	SetOutPath $0\import\dist
+	File ${VIMRT}\import\dist\*.*
+
 	SetOutPath $0\bitmaps
 	File ${VIMSRC}\vim.ico
 
@@ -1044,6 +1047,7 @@
 	RMDir /r $0\compiler
 	RMDir /r $0\doc
 	RMDir /r $0\ftplugin
+	RMDir /r $0\import
 	RMDir /r $0\indent
 	RMDir /r $0\macros
 	RMDir /r $0\pack