Add support for OSX to intellij-gen.sh

Remove the hardcoded "linux-x86" path, and add support for darwin-x86.

Change-Id: I4c5db4683a6e8aac7d894e64415142d2ca5954a2
diff --git a/tools/idegen/intellij-gen.sh b/tools/idegen/intellij-gen.sh
index 860bd3c..3c4efc5 100755
--- a/tools/idegen/intellij-gen.sh
+++ b/tools/idegen/intellij-gen.sh
@@ -54,7 +54,11 @@
 idegenjar=$script_dir/idegen.jar
 if [ ! -e $idegenjar ]; then
   # See if the jar is in the build directory.
-  idegenjar=$root_dir/out/host/linux-x86/framework/idegen.jar
+  platform="linux"
+  if [ "Darwin" = "$(uname)" ]; then
+    platform="darwin"
+  fi
+  idegenjar="$root_dir/out/host/$platform-x86/framework/idegen.jar"
 fi
 
 if [ ! -e "$index_file" ]; then