win32_deps_build.sh: avoid duplicate boost definitions

win32_deps_build.sh: avoid duplicate boost definitions

Boost stacktrace defines a few UUIDs that were recently added
to mingw as well [1], causing compilation errors [2]:

  In file included from libs/stacktrace/build/../src/windbg.cpp:9:
  ./boost/stacktrace/detail/frame_msvc.ipp:31:5: error: redefinition of
    '__mingw_uuidof_s<IDebugClient>'
    __CRT_UUID_DECL(IDebugClient,0x27fe5639,...

We'll apply a fix that hasn't merged upsteam yet [3].

[1] https://github.com/mirror/mingw-w64/commit/ce5a9f624dfc691082dad2ea2af7b1985e3476b5
[2] https://github.com/boostorg/stacktrace/issues/133
[3] https://github.com/boostorg/stacktrace/pull/140

Signed-off-by: Lucian Petrut <lpetrut@cloudbasesolutions.com>