[libcxx] Set LC_ALL rather than LC_COLLATE to override collation.

r251131 replaced LANG with LC_COLLATE. But LC_ALL has precedence
over both, so the test still fails when LC_ALL=C.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@257018 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/std/localization/locale.categories/category.collate/locale.collate.byname/transform.pass.cpp b/test/std/localization/locale.categories/category.collate/locale.collate.byname/transform.pass.cpp
index 04cc060..d31705e 100644
--- a/test/std/localization/locale.categories/category.collate/locale.collate.byname/transform.pass.cpp
+++ b/test/std/localization/locale.categories/category.collate/locale.collate.byname/transform.pass.cpp
@@ -26,7 +26,7 @@
 int main()
 {
     // Ensure that the default locale is not C.  If it is, the second tests will fail.
-    putenv(const_cast<char*>("LC_COLLATE=" LOCALE_en_US_UTF_8));
+    putenv(const_cast<char*>("LC_ALL=" LOCALE_en_US_UTF_8));
     {
         std::locale l(LOCALE_en_US_UTF_8);
         {