Recognise DEC C++ as equivalent to DEC C for the definitions of OPENSSL_EXTERN and OPENSSL_GLOBAL.
Submitted by Compaq.

e_os2.h

diff --git a/e_os2.h b/e_os2.h
index ea92ff5..9c4a541 100644
--- a/e_os2.h
+++ b/e_os2.h
@@ -131,6 +131,9 @@
 # define OPENSSL_SYS_VMS
 # if defined(__DECC)
 #  define OPENSSL_SYS_VMS_DECC
+# elif defined(__DECCXX)
+#  define OPENSSL_SYS_VMS_DECC
+#  define OPENSSL_SYS_VMS_DECCXX
 # else
 #  define OPENSSL_SYS_VMS_NODECC
 # endif