Add pg_attribute_always_inline.
Add pg_attribute_always_inline.

Sometimes it is useful to be able to insist that the compiler inline a
function that its normal cost analysis would not normally choose to inline.
This can be useful for instantiating different variants of a function that
remove branches of code by constant folding.

Author: Thomas Munro
Reviewed-By: Andres Freund
Discussion: 14029419d87b7d01d9023a7f86d41fe3b2b4b6e1@mail.gmail.com

50wu/gpdb,xinzweb/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,xinzweb/gpdb,adam8157/gpdb,50wu/gpdb,lisakowen/gpdb,50wu/gpdb,greenplum-db/gpdb,xinzweb/gpdb,xinzweb/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,50wu/gpdb,xinzweb/gpdb,lisakowen/gpdb,lisakowen/gpdb,50wu/gpdb,lisakowen/gpdb,adam8157/gpdb,lisakowen/gpdb,adam8157/gpdb,greenplum-db/gpdb,50wu/gpdb,adam8157/gpdb,xinzweb/gpdb,adam8157/gpdb,greenplum-db/gpdb,adam8157/gpdb,greenplum-db/gpdb,adam8157/gpdb,xinzweb/gpdb,50wu/gpdb,xinzweb/gpdb,lisakowen/gpdb,lisakowen/gpdb,lisakowen/gpdb,adam8157/gpdb,50wu/gpdb