Silence a -Wmissing-braces warning in the tests; mbstate_t is defined differently on different C libraries.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@254050 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/std/depr/depr.c.headers/wchar_h.pass.cpp b/test/std/depr/depr.c.headers/wchar_h.pass.cpp
index c4a218b..e561b3e 100644
--- a/test/std/depr/depr.c.headers/wchar_h.pass.cpp
+++ b/test/std/depr/depr.c.headers/wchar_h.pass.cpp
@@ -31,7 +31,15 @@
 
 int main()
 {
+// mbstate_t comes from the underlying C library; it is defined (in C99) as:
+//    a complete object type other than an array type that can hold the conversion 
+//    state information necessary to convert between sequences of multibyte 
+//    characters and wide characters
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wmissing-braces"
     mbstate_t mb = {0};
+#pragma clang diagnostic pop
+
     size_t s = 0;
     tm *tm = 0;
     wint_t w = 0;