Add support for JRuby 9000 bundled with the Graal VM

JRuby 9000 (the next major release) includes a backend that supports a
new JVM JIT compiler called Graal. Graal is based on OpenJDK but hasn't
been released yet.

http://openjdk.java.net/projects/graal/

bin/ruby-build

@@ -519,10 +519,29 @@ build_package_jruby() {
   fix_jruby_shebangs
 }
 
+graal_architecture() {
+  if [ "$(uname -m)" != "x86_64" ]; then
+    echo "no nightly builds available" >&2
+    exit 1
+  fi
+
+  case "$(uname -s)" in
+  "Darwin") echo "macosx-x86_64";;
+  "Linux") echo "linux-x86_64";;
+  *)
+    echo "no nightly builds available" >&2
+    exit 1;;
+  esac
+}
+
 install_jruby_launcher() {
-  cd "${PREFIX_PATH}/bin"
-  { ./ruby gem install jruby-launcher
-  } >&4 2>&1
+  # If this version of JRuby has been modified for Graal, don't overwrite the
+  # launcher scripts
+  if ! grep -q graalvm "${PREFIX_PATH}/bin/jruby"; then
+    cd "${PREFIX_PATH}/bin"
+    { ./ruby gem install jruby-launcher
+    } >&4 2>&1
+  fi
 }
 
 fix_jruby_shebangs() {

share/ruby-build/jruby-9000+graal-dev

@@ -0,0 +1 @@
+install_package "jruby-9000.dev" "http://lafo.ssw.uni-linz.ac.at/graalvm/jruby-dist-9000+graal-$(graal_architecture).dev-bin.tar.gz" jruby