Add runtime-path to DynamicLinking.md

[hoodmane]

Changes to the conventions for #244.

cc @ryanking13 @sbc100.

[hoodmane]

@sbc100 are there other people I should ask to review this?

[sunfishcode]

I wonder of @dicej has any thoughts here, from the perspective of componentize-py.

[hoodmane]

This is important for truly-at-runtime dynamic linking, but I'd think not really necessary for "componentize" dynamic linking. Maybe if there is an "install" step before componentizing it could be easier to use the rpath, but nothing that couldn't be managed by patching around the build scripts a bit. But I agree it'd be interesting to hear @dicej's opinion.

[sbc100]

lgtm % comments from others.

Adding @dschuff too

[dicej]

This is important for truly-at-runtime dynamic linking, but I'd think not really necessary for "componentize" dynamic linking. Maybe if there is an "install" step before componentizing it could be easier to use the rpath, but nothing that couldn't be managed by patching around the build scripts a bit. But I agree it'd be interesting to hear @dicej's opinion.

Yeah, I'm not sure how componentize-py would use this offhand, although maybe it could help with finding needed .so files at component build time. I've got no objections to this PR, in any case.