Avoid implementation defined behavior in a test.

Summary:
num_put::put uses %p for pointer types, but the exact format of %p is
implementation defined behavior for the C library. Compare output to
snprintf for portability.

Reviewers: EricWF, mclow.lists

Reviewed By: EricWF

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D29197

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@293926 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed