Packaging for Linux in a binary build should be disabled when not supported

According to the user, if you install Linux toolchain, the binary build will allow you to package for it, and will not handle the failure gracefully ( https://forums.unrealengine.com/showthread.php?54636-Linux-cross-compilation-on-4-6-1-(binary-version) )

What should happen instead depends on the version:

• for 4.6.x and older, the option to package should perhaps not appear at all in a binary version, no matter whether the toolchain is installed.
• for 4.7 we want to support packaging of content-only builds.

1) Install Linux toolchain as described in [Link Removed]

2) Run the binary version (from the Launcher)

3) Try to package a content-only project for Linux.

4) Try to package a code project for Linux.