Reinstate failglob behaviour for most commands

Expand globs to zero arguments (nullglob) only for set, for and count.

The warning about failing globs, and setting the accompanying $status,
now happens regardless of mode, interactive or not.

It is assumed that the above commands are the common cases where
nullglob behaviour is desirable.
More importantly, doing this with `set` is a real feature enabler,
since the resulting empty array can be passed on to any command.

The previous behaviour was actually all nullglob (since commit
cab115c8b9), but this was undocumented;
the failglob warning was still printed in interactive mode,
and the documentation was bragging about failglob behaviour.

tests/test5.err

@@ -0,0 +1,3 @@
+No matches for wildcard '*ee*'.
+fish: 	case *ee*
+      	     ^