The default locale "" should be a UTF-8 locale.

"ls -q" (or "adb shell -tt ls") was mangling non-ASCII because mbrtowc
was returning multibyte characters as their individual bytes. This was
because toybox asks for "" rather than "C.UTF-8", and for some reason
we were interpreting that as "C" rather than "C.UTF-8".

Test: bionic tests, ls
Change-Id: Ic60e3b90cd5fe689e5489fad0d5d91062b9594ed
diff --git a/tests/locale_test.cpp b/tests/locale_test.cpp
index f308af5..8b38c40 100644
--- a/tests/locale_test.cpp
+++ b/tests/locale_test.cpp
@@ -59,9 +59,10 @@
   EXPECT_EQ(EINVAL, errno);
 
 #if defined(__BIONIC__)
-  // The "" locale is implementation-defined. For bionic, it's the C locale.
+  // The "" locale is implementation-defined. For bionic, it's the C.UTF-8 locale, which is
+  // pretty much all we support anyway.
   // glibc will give us something like "en_US.UTF-8", depending on the user's configuration.
-  EXPECT_STREQ("C", setlocale(LC_ALL, ""));
+  EXPECT_STREQ("C.UTF-8", setlocale(LC_ALL, ""));
 #endif
   EXPECT_STREQ("C", setlocale(LC_ALL, "C"));
   EXPECT_STREQ("C", setlocale(LC_ALL, "POSIX"));