VMS: throw away [.util]shareable_image_wrap.c.in and add replacement scripts

[.util]shareable_image_wrap.c.in was never useful because lib$spawn()
insisted on combining stdout and stderr into one.

Instead, we introduce two scripts that create and destroy a temporary
environment where the local shareable images become available,
[.util]local_shlib.com and [.util]unlocal_shlib.com.  They also define
DBG$IMAGE_DSF_PATH, which is require so the debugger can find the Debug
Symbol Files.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2947)