mame: improve user experience when running

[mascguy (Christopher Nielsen)]

Presently, when launching Mame, the user is presented with several warnings:

$ mame
Unable to create history.db

Unable to create history.db

This is due to the default Mame configuration, which references read-only directories within the MacPorts tree.

For the next port release, we should improve on this:

• At a minimum, the port notes should mention that a custom user configuration file (.ini) will fix such issues.
• In addition, it would be helpful to provide an example user configuration file.
• And finally, it might also be worth using a default configuration, that references user-writable areas. Say, ~/Library/Application Support/Mame/

Another consideration, is the Mame tools:

• Currently, no soft links are created in ${prefix}/bin, for those additions.
• For the next release, we should consider creating those... perhaps with a variant option to enable/disable.
• To avoid possible clashes, consider adding a 'mame-' prefix to said links. (But need to verify that no issues are caused by that. For example, if any tool invokes another... that could be problematic. Net-Net, more testing/verification/investigation needed beforehand.)

[mascguy (Christopher Nielsen)]

A semi-related ticket -- albeit targeted at non-user-facing port cleanup -- is: issue:61739