Rename unittests/ADT/ilistTestTemp.cpp => IListTest.cpp

Rename unittests/ADT/ilistTestTemp.cpp => IListTest.cpp

And rename the tests inside from ilistTest to IListTest.  This makes the
file sort properly in the CMakeLists.txt (previously, sorting would
throw it down to the end of the list) and is consistent with the tests
I've added more recently.

Why use IListNodeBaseTest.cpp (and a test name of IListNodeBaseTest)?
- ilist_node_base_test is the obvious thing, since this is testing
  ilist_node_base.  However, gtest disallows underscores in test names.
- ilist_node_baseTest fails for the same reason.
- ilistNodeBaseTest is weird, because it isn't in our usual
  TitleCaseTest form that we use for tests, and it also doesn't have the
  name of the tested class in it.
- IlistNodeBaseTest matches TitleCaseTest, but "Ilist" is hard to read,
  and really "ilist" is an abbreviation for "IntrusiveList" so the
  lowercase "list" is strange.
- That left IListNodeBaseTest.

Note: I made this move in two stages, with a temporary filename of
ilistTestTemp in between in r279524.  This was in the hopes of avoiding
problems on Git and SVN clients on case-insensitive filesystems,
particularly on buildbots with incremental checkouts.

llvm-svn: 280033