Add checkpoint diagnostics to help diagnose buildbot failures.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@275754 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/localization/locale.categories/category.ctype/locale.ctype.byname/types.pass.cpp

@@ -28,10 +28,12 @@
 #include <cassert>
 
 #include "platform_support.h" // locale name macros
+#include "assert_checkpoint.h"
 
 int main()
 {
     {
+        CHECKPOINT("constructing en-US.UTF-8");
         std::locale l(LOCALE_en_US_UTF_8);
         {
             assert(std::has_facet<std::ctype_byname<char> >(l));
@@ -45,6 +47,7 @@ int main()
         }
     }
     {
+        CHECKPOINT("constructing default locale");
         std::locale l("");
         {
             assert(std::has_facet<std::ctype_byname<char> >(l));
@@ -58,6 +61,7 @@ int main()
         }
     }
     {
+        CHECKPOINT("constructing C locale");
         std::locale l("C");
         {
             assert(std::has_facet<std::ctype_byname<char> >(l));