VMS: Fix the passing of cflags for things not being installed

When building object files for libraries, information whether the
library would be installed or not wasn't passed down to the object
file building rules.

Also, make it so settings like |no_inst_lib_cflags| can be the empty
string.

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3247)