Edit Troubleshooting.md for Linuxbrew
Edit Troubleshooting.md for Linuxbrew

Edit Troubleshooting.md to remove references to Apple Xcode.

Closes Linuxbrew/linuxbrew#317.

Signed-off-by: Shaun Jackman <b580dab3251a9622aba3803114310c23fdb42900@gmail.com>

maxim-belkin/brew,Linuxbrew/brew,hanxue/linuxbrew,rwhogg/brew,Linuxbrew/brew,Linuxbrew/brew,Linuxbrew/brew,hanxue/linuxbrew,rwhogg/brew,maxim-belkin/brew,maxim-belkin/brew,hanxue/linuxbrew,rwhogg/brew