Ubuntu needs the post-install hook to be run

(cherry picked from commit 1c9bc59)

Author: chrisseaton

doc/user/installing-libssl.md

@@ -22,6 +22,10 @@ We recommend `libssl-dev` instead of `libssl1.0.0`, even though we aren't using
 it for development because the latter doesn't seem to put the shared library in
 a place where we can find it.
 
+After installing GraalVM and Ruby you will need to rebuild `openssl` for the
+version in Ubuntu - run `lib/truffle/post_install_hook.sh`. Make sure you run
+it with TruffleRuby on your `$PATH`.
+
 ## Fedora
 
 On Fedora 25 or older, the default openssl is correct, so you only need to

tool/docker-configs.yaml

@@ -79,6 +79,7 @@ ol7:
   cppext:
     - RUN yum install -y libcxx libcxx-devel
   rvm:
+  post-install: false
 ubuntu1604:
   base: ubuntu:16.04
   setup:
@@ -104,6 +105,7 @@ ubuntu1604:
   cppext:
     - RUN apt-get install -y libc++-dev
   rvm:
+  post-install: true
 fedora25:
   base: fedora:25
   setup:
@@ -129,3 +131,4 @@ fedora25:
     - RUN dnf install -y libcxx
   rvm:
     - RUN dnf install -y procps
+  post-install: false

tool/jt.rb

@@ -2007,6 +2007,7 @@ def dockerfile(*args)
       lines.push "RUN $D_GRAALVM_BASE/bin/gu install /test/#{graalvm_component}"
       lines.push "ENV D_RUBY_BASE=$D_GRAALVM_BASE/jre/languages/ruby"
       lines.push "ENV D_RUBY_BIN=$D_GRAALVM_BASE/bin"
+      lines.push "RUN PATH=$D_RUBY_BIN:$PATH $D_RUBY_BASE/lib/truffle/post_install_hook.sh" if distro.fetch('post-install')
     when :source
       lines.push "RUN git clone --depth 1 https://github.com/graalvm/mx.git"
       lines.push "ENV PATH=$PATH:/test/mx"