tools: enable final newline in .editorconfig

PR-URL: https://github.com/nodejs/node/pull/9410
Fixes: https://github.com/nodejs/node/issues/9402
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Minwoo Jung <jmwsoft@gmail.com>

.editorconfig

@@ -4,6 +4,7 @@ root = true
 end_of_line = lf
 charset = utf-8
 trim_trailing_whitespace = true
+insert_final_newline = true
 
 [vcbuild.bat]
 end_of_line = crlf
@@ -37,3 +38,6 @@ indent_size = ignore
 end_of_line = ignore
 trim_trailing_whitespace = ignore
 charset = ignore
+
+[{test/fixtures,deps,tools/eslint,tools/gyp,tools/icu,tools/msvs}/**]
+insert_final_newline = false