Code health: Quick note in changes and the OPENSSL_GLOBAL et al changes

Reviewed-by: NAndy Polyakov <appro@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2785)

CHANGES

@@ -4,6 +4,10 @@
 
  Changes between 1.1.0e and 1.1.1 [xx XXX xxxx]
 
+  *) Remove VAX C specific definitions of OPENSSL_EXPORT, OPENSSL_EXTERN.
+     Also remove OPENSSL_GLOBAL entirely, as it became a no-op.
+     [Richard Levitte]
+
   *) Remove the VMS-specific reimplementation of gmtime from crypto/o_times.c.
      VMS C's RTL has a fully up to date gmtime() and gmtime_r() since V7.1,
      which is the minimum version we support.