[test] [re.traits] Remove asserts failing due to invalid UTF-8

Remove the two test cases for \xDA and \xFA with UTF-8 locale, as both
characters alone are invalid in UTF-8 (short sequences).  Upon removing
them, the test passes on Linux again (and also on NetBSD, after adding
appropriate locale configuration).

Differential Revision: https://reviews.llvm.org/D55746

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@349378 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/re/re.traits/translate_nocase.pass.cpp

@@ -19,9 +19,6 @@
 // XFAIL: with_system_cxx_lib=macosx10.7
 // XFAIL: with_system_cxx_lib=macosx10.8
 
-// TODO: investigation needed
-// XFAIL: linux-gnu
-
 #include <regex>
 #include <cassert>
 
@@ -47,8 +44,6 @@ int main()
         assert(t.translate_nocase('.') == '.');
         assert(t.translate_nocase('a') == 'a');
         assert(t.translate_nocase('1') == '1');
-        assert(t.translate_nocase('\xDA') == '\xFA');
-        assert(t.translate_nocase('\xFA') == '\xFA');
     }
     {
         std::regex_traits<wchar_t> t;