raco decompile: fix for `#%foreign`

Merge to v6.0.1
(cherry picked from commit e9b97c494c5dbe3fe27d29f18a1f93a3dcfffc5f)
racket/undefined: remove `undefined?` and `check-not-undefined`

The intent is to provide a minimal bridge between the current Racket
and one where `(letrec ([x x]) x)` no longer works.

Merge to v6.0.1
(cherry picked from commit 83a573ccd8b216d9600435692dfa4da851a55d91)
Show a REPL type printing example in the TR guide

Please merge to v6.0.1
(cherry picked from commit 52cc507aa5dc4e8825c1dd3f8ad5516f969b2732)
Fix `identifier-binding` docs and types

Closes PR 14262

Please merge to v6.0.1
(cherry picked from commit 5eb1110040f73f21b68329c90fa3eee369dc5357)
Fix internal-external name mapping for TR classes

Please merge to v6.0.1
(cherry picked from commit a11144c8f85d0d0c788e8139c22ed663dd7f5597)
Fix types in typed/file/gif

Thanks to WarGrey Gyoudmon Ju for reporting the bug

Please merge to v6.0.1
(cherry picked from commit 8c1206c06303b5ee3635bec2c04c6b8b594fd2ea)
openssl: recognize version 1.0.1g

Merge to v6.0.1
(cherry picked from commit 145dc95b874f4566b213723962bf7df2fef254f4)
fix problem with `syntax-local-lift-require`

Closes PR 13797

Merge to v6.0.1
(cherry picked from commit 414507699ba8f71a7b3630b833a4b4582a49dd57)
avoid overflow in poll() timeout calculation

Closes PR 14410

Merge to v6.0.1
(cherry picked from commit 393456563e2562c8e6358705328dbc4b059cad37)
upgrade Windows OpenSSL libraries to 1.0.1g
Remove Redex benchmark from the release branch.