report headers/library/ABI version

[remicollet]

Try to improve phpinfo output

• headers version is buildtime
• library version is runtime
• ABI is... perhaps uneeded

Can also consider removing the major/minor/patch above

[remicollet]

Notice, lot of extension provides headers/library version in this way.
Could be useful for "support" to better understand user env.

[jcupitt]

Thank you @remicollet, that looks useful.