Attaching metadata references to global variables

[syegulalp]

Is this possible in llvmlite? It doesn't appear to be documented, or exposed through the API set for objects like llvmlite.ir.GlobalVariable.

[sklam]

Looks like we didn't add it for GlobalVariable. Looks like it's not too hard to do. Just need to add _HasMetadata and the required attributes to GlobalVariable

[john-tornblom]

See PR #760