Follow up to r1345883; protect macro arguments.
Follow up to r1345883; protect macro arguments.

* subversion/libsvn_subr/string.c
  (COPY_TWO_BYTES):
    Wrap the two macro arguments in ().


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1345993 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion