the -fpcc-struct-return calling convention properly instead of
returning garbage. This may break backwards compatibility with some old
binaries that were compiled when -fno-pcc-struct-return was the default.
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.