Fix MacOS build for 1.0-maint (#5135)

use rbenv openssl 1.0 so it doesn't use openssl 1.1.

Homebrew formula python-build option

Docs aren't great but looks like you can specify a homebrew formula to use. If you don't, it looks like python-build ends up trying to use 1.1.

https://github.com/pyenv/pyenv/blob/b1381d1d4630c5fb73517b78d68939663635311f/plugins/python-build/bin/python-build#L1512

https://github.com/pyenv/pyenv/pull/1328

.travis/install.sh

@@ -9,10 +9,10 @@ if [[ "$(uname -s)" == 'Darwin' ]]; then
     export HOMEBREW_TEMP=~/brew-temp
     mkdir $HOMEBREW_LOGS
     mkdir $HOMEBREW_TEMP
-    # brew update
-    if [[ "${OPENSSL}" != "0.9.8" ]]; then
-        brew outdated openssl || brew upgrade openssl
-    fi
+
+    # Brew removed [email protected] end of 2019 https://brew.sh/2019/11/27/homebrew-2.2.0/
+    # Use rbenv's formula fork https://github.com/rbenv/homebrew-tap/blob/master/Formula/openssl%401.0.rb
+    brew install rbenv/tap/[email protected]
 
     if which pyenv > /dev/null; then
         eval "$(pyenv init -)"
@@ -25,11 +25,11 @@ if [[ "$(uname -s)" == 'Darwin' ]]; then
 
     case "${TOXENV}" in
         py34)
-            pyenv install 3.4.5
+            PYTHON_BUILD_HOMEBREW_OPENSSL_FORMULA=[email protected] pyenv install 3.4.5
             pyenv global 3.4.5
             ;;
         py35)
-            pyenv install 3.5.2
+            PYTHON_BUILD_HOMEBREW_OPENSSL_FORMULA=[email protected] pyenv install 3.5.2
             pyenv global 3.5.2
             ;;
         py36)