clang/test/CXX/drs/dr2xx.cpp: Suppress this for targeting LLP64 due to __SIZE_TYPE__.

  Line 559: 'long long' is a C++11 extension
  Line 566: 'long long' is a C++11 extension
  Line 674: 'long long' is a C++11 extension

See also PR13819.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@195005 91177308-0d34-0410-b5e6-96231b3b80d8