Simplify our use of ucnv_close.

ucnv_close -- like most modern "free" APIs -- ignores NULL. It also calls each
callback giving it a convenient opportunity to clean up, which lets us get rid
of some particularly nasty code that was trying to do the cleanup forcibly from
outside.

Change-Id: I77ccf37235a222f38d897516d1226a026d8cc50b
1 file changed