message: [lldb] [lit/Register] Fix test to use %clangxx
diff: # REQUIRES: native && (target-x86 || target-x86_64)
  -# RUN: %clang++ %p/Inputs/x86-mm-xmm-read.cpp -o %t
  +# RUN: %clangxx %p/Inputs/x86-mm-xmm-read.cpp -o %t
  # RUN: %lldb -b -s %s %t | FileCheck %s
  process launch
  