openvms: fix OpenSSL discovery on VAX

The DCL code had a typo in one of the commands which would make the
OpenSSL discovery on VAX fail. The correct syntax is F$ENVIRONMENT.

Closes #3407
Reviewed-by: Viktor Szakats <commit@vszakats.net>

packages/vms/generate_config_vms_h_curl.com

@@ -406,7 +406,7 @@ $   write cvh "#define USE_OPENSSL 1"
 $   write cvh "#endif"
 $   if arch_name .eqs. "VAX"
 $   then
-$       old_mes = f$enviroment("message")
+$       old_mes = f$environment("message")
 $       set message/notext/nofaci/noseve/noident
 $       search/output=nla0: ssl$include:*.h CONF_MFLAGS_IGNORE_MISSING_FILE
 $       status = $severity