Log Message:
Update to 2.2.3

Upstream Changelog is large; bug fixes are omitted and heaeders only
follow; see NEWS for details.

Changes in 2.2.3 (since 2.2.2):

* New interfaces and functionality

** (web uri) module has better support for RFC 3986

** `struct-ref/unboxed' and `struct-set!/unboxed'

** Improved support for arrays with non-zero lower bounds

** Add `uintptr_t' and `intptr_t' to FFI types.

* Compiler improvements

** Improve speed of compiler backend for functions without loops

** Disable slot pre-coloring for optimization level "-O1" or below

** Improve complexity of constant subexpression elimination pass

** CPS conversion avoids generating return arity adapters if possible

* New deprecations

** Using `uri?' as a predicate on relative-refs deprecated

** Struct tail arrays deprecated

** Struct "self" slots deprecated

** Struct fields with opaque ("o") protection deprecated

** Using `struct-ref' and `struct-set!' on unboxed fields is deprecated

Changes in 2.2.2 (since 2.2.1):

Changes in 2.2.1 (since 2.2.0):

* Notable changes

** New sandboxed evaluation facility

** All literal constants are read-only

** Syntax objects are now a distinct type