In dbcommands.c function createdb(), there are several sets of very
similar local variable names, such as "downer" and "dbowner", which is
very confusing and error-prone. The first set are the DefElem nodes
from the parser, the second set are the local variables with the values
extracted from them. This patch renames the former to "ownerEl" and so
on, similar to collationcmds.c and typecmds.c, to improve clarity.