Add a parse location field to struct FunctionParameter.

Add a parse location field to struct FunctionParameter.

This allows an error cursor to be supplied for a bunch of
bad-function-definition errors that previously lacked one,
or that cheated a bit by pointing at the contained type name
when the error isn't really about that.

Bump catversion from an abundance of caution --- I don't think
this node type can actually appear in stored views/rules, but
better safe than sorry.

Jian He and Tom Lane (extracted from a larger patch by Jian,
with some additional work by me)

Discussion: https://postgr.es/m/CACJufxEmONE3P2En=jopZy1m=cCCUs65M4+1o52MW5og9oaUPA@mail.gmail.com