Add CPython 3.8.4rc1

plugins/python-build/share/python-build/3.8.4rc1

@@ -0,0 +1,10 @@
+#require_gcc
+prefer_openssl11
+export PYTHON_BUILD_CONFIGURE_WITH_OPENSSL=1
+install_package "openssl-1.1.0j" "https://www.openssl.org/source/old/1.1.0/openssl-1.1.0j.tar.gz#31bec6c203ce1a8e93d5994f4ed304c63ccf07676118b6634edded12ad1b3246" mac_openssl --if has_broken_mac_openssl
+install_package "readline-8.0" "https://ftpmirror.gnu.org/readline/readline-8.0.tar.gz#e339f51971478d369f8a053a330a190781acb9864cf4c541060f12078948e461" mac_readline --if has_broken_mac_readline
+if has_tar_xz_support; then
+  install_package "Python-3.8.4rc1" "https://www.python.org/ftp/python/3.8.4/Python-3.8.4rc1.tar.xz#d73df3cb2b56f73a78650b44112a6a2ce6b0e8961f277b4f253024b633b93e2c" ldflags_dirs standard verify_py38 copy_python_gdb ensurepip
+else
+  install_package "Python-3.8.4rc1" "https://www.python.org/ftp/python/3.8.4/Python-3.8.4rc1.tgz#b11b9c1b362804022b4329c76644ba17dbc36ff7cd4503624adb3de52d3dfbde" ldflags_dirs standard verify_py38 copy_python_gdb ensurepip
+fi