When we redid the database statistics configuration, we configured the wt
command's wiredtiger_open call to configure statistics=(all), which makes
the "wt stat -a" option to print all of the statistics unnecessary, that's
going to be the default if nothing is specified to the statistics cursor.
However, we do need -f, to override the default configuration to report
only the "fast" statistics.

Leave the -a option in, but it doesn't have any effect.
Merge pull request #1519 from wiredtiger/command-stat

Rework "wt stat" command-line arguments.