This reverts commit 9f984ba6d23dc6eecebf479ab1d3f2e550a4e9be.
It was making the buildfarm unhappy, apparently setting client_min_messages
in a regression test produces different output if log_statement='all'.
Another issue is that I now suspect the bit sortsupport function was in
fact not correct to call byteacmp(). Revert to investigate both of those
issues.
This will allow enums to be used in exclusion constraints.
The code uses the new CallerFInfoFunctionCall infrastructure in fmgr,
and the support for it added to btree_gist in commit 393bb504d7.
Reviewed by Tom Lane and Anastasia Lubennikova
Discussion: http://postgr.es/m/56EA8A71.8060107@dunslane.net