[libcxx] [test] Silence warning C4324 for MSVC.

This warning "structure was padded due to alignment specifier" says
that the compiler is going to do exactly what you asked it to do.
It's triggered by the tests for over-aligned dynamic memory allocation.

llvm-svn: 314257

libcxx/test/support/msvc_stdlib_force_include.hpp

@@ -54,6 +54,7 @@ const AssertionDialogAvoider assertion_dialog_avoider{};
 
     // Silence compiler warnings.
     #pragma warning(disable: 4180) // qualifier applied to function type has no meaning; ignored
+    #pragma warning(disable: 4324) // structure was padded due to alignment specifier
     #pragma warning(disable: 4521) // multiple copy constructors specified
     #pragma warning(disable: 4702) // unreachable code
     #pragma warning(disable: 28251) // Inconsistent annotation for 'new': this instance has no annotations.