Added stackless-3.5.4

plugins/python-build/share/python-build/stackless-3.5.4

@@ -0,0 +1,4 @@
+#require_gcc
+install_package "openssl-1.0.2k" "https://www.openssl.org/source/openssl-1.0.2k.tar.gz#6b3977c61f2aedf0f96367dcfb5c6e578cf37e7b8d913b4ecb6643c3cb88d8c0" mac_openssl --if has_broken_mac_openssl
+install_package "readline-6.3" "https://ftpmirror.gnu.org/readline/readline-6.3.tar.gz#56ba6071b9462f980c5a72ab0023893b65ba6debb4eeb475d7a563dc65cafd43" standard --if has_broken_mac_readline
+install_package "stackless-3.5.4-slp" "https://github.com/stackless-dev/stackless/archive/v3.5.4-slp.tar.gz#ddb65a8118c754f66875f65c4d5d2a4937d67858ec8c361a6c5b386f5e4d9fce" ldflags_dirs standard verify_py35 ensurepip