[sanitizer_common] Define wordexp_wrde_dooffs for Solaris

The Solaris buildbots have been broken for some time:

  In file included from /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/llvm/compiler-rt/lib/asan/asan_interceptors.cpp:174:
  /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/llvm/compiler-rt/lib/asan/../sanitizer_common/sanitizer_common_interceptors.inc:4000:19: error: use of undeclared identifier 'wordexp_wrde_dooffs'
          ((flags & wordexp_wrde_dooffs) ? p->we_offs : 0) + p->we_wordc;
                    ^

This was caused by D108646 <https://reviews.llvm.org/D108646>; the fix is
equivalent to D108838 <https://reviews.llvm.org/D108838>.

Tested on `amd64-pc-solaris2.11` and `sparcv9-sun-solaris2.11`.

Differential Revision: https://reviews.llvm.org/D109193