message: guix: Don't set MINGW_HAS_SECURE_API CFLAG in depends
  This is no longer needed after in the mingw-w64 git repository,
  which is first included in mingw-w64 v7.0.0.
  As of the previous bump to our Guix time machine, we now use mingw-w64
  v7.0.0.
diff: @@ -134,8 +134,7 @@ make -C depends --jobs="$MAX_JOBS" HOST="$HOST" \
  x86_64_linux_RANLIB=x86_64-linux-gnu-ranlib \
  x86_64_linux_NM=x86_64-linux-gnu-nm \
  x86_64_linux_STRIP=x86_64-linux-gnu-strip \
  - qt_config_opts_i686_linux='-platform linux-g++ -xplatform bitcoin-linux-g++' \
  - mingw32_CFLAGS='-DMINGW_HAS_SECURE_API=1 -pipe'
  + qt_config_opts_i686_linux='-platform linux-g++ -xplatform bitcoin-linux-g++'
  ###########################
  