openssl: basic dbg package

[xnox]

Add a basic manual dbg package for openssl.

Install source code into /usr/src/${{package.name}} (maybe needs a pipeline like that).

Use -g to create debug symbols and file-prefix-map to encode all source code references in the debug symbols to that destination.

Use split/debug as the first subpackage to detach all debug.

Note build-ids are not set by split/debug pipeline, meaning these debug symbols are not suitable to upload into debuginfod server. See https://sourceware.org/elfutils/Debuginfod.html

But this will do for now, installing openssl-dbg allows gdb to just work. This is needed to stream-line security lab assesments, but also to debug OpenSSL features and bugs.

Landing this requires https://github.com/chainguard-dev/melange/pull/1555 to make it into every builder type.