.gitignore update for x86 arch

This patch:
- makes .gitignore files visible to git
- makes arch/x86/kernel/vsyscall_32.lds and arch/i386/boot invisible

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>