The benefit with using configdata.pm is that Configure writes it for
us.
Reviewed-by: NViktor Dukhovni <viktor@openssl.org>

This isn't the fully featured combination of compiler generated
dependency files and Makefile include directives, but a cheaper
variant of the same.

The dependency files are generated automatically, but then we have the
usual "depend" target.  However, we depend on it in the bigger phony
targets that are the most likely to be used.  That make this feature
automatic enough.

A side effect is that we can't use the build file's timestamp to check
if reconfiguring might be in order.  In its place, we use a flag file
that depends on Configure and the build file template and depend on it
in spots where it makes sense to check for the need to reconfigure.
Reviewed-by: NRich Salz <rsalz@openssl.org>

.d (.MMS in the VMS world) files with just dependencies are built from
exactly the same conditions as the object files.  Therefore, the rules
for them can be built at the same time as the rules for the
corresponding object files.

This removes the requirement for a src2dep function in the build file
templates, and for common.tmpl to call it.  In the end, the existence
of depend files is entirely up to the build file.
Reviewed-by: NRich Salz <rsalz@openssl.org>

Reviewed-by: NRichard Levitte <levitte@openssl.org>

Reviewed-by: NViktor Dukhovni <viktor@openssl.org>

Reviewed-by: NViktor Dukhovni <viktor@openssl.org>

Test programs are now only built when running "make test" or "make
build_tests".
Reviewed-by: NRich Salz <rsalz@openssl.org>

Otherwise, there will be an unbalance.
Reviewed-by: NRich Salz <rsalz@openssl.org>

There was a catch 22, where 'make depend' directly after configuring
in an otherwise pristine build tree would fail because buildinf.h
didn't exist yet.

This change has the depend building targets depend on the same other
targets as the object file building targets, so the generation of
buildinf.h and similar files would kick in during 'make depend'.
Reviewed-by: NRich Salz <rsalz@openssl.org>

INSTALL_PREFIX is a confusing name, as there's also --prefix.
Instead, tag along with the rest of the open source world and adopt
the Makefile variable DESTDIR to designate the desired staging
directory.

The Configure option --install_prefix is removed, the only way to
designate a staging directory is with the Makefile variable (this is
also implemented for VMS' descrip.mms et al).
Reviewed-by: NRich Salz <rsalz@openssl.org>

As part of this, change util/mkdef.pl to stop adding libraries to
depend on in its output.  mkdef.pl should ONLY output a symbol
vector.

Because symbol names can't be longer than 31 characters, we use the
compiler to shorten those that are longer down to 23 characters plus
an 8 character CRC.  To make sure users of our header files will pick
up on that automatically, add the DEC C supported extra headers files
__decc_include_prologue.h and __decc_include_epilogue.h.

Furthermore, we add a config.com, so VMS people can configure just as
comfortably as any Unix folks, thusly:

    @config
Reviewed-by: NRich Salz <rsalz@openssl.org>