x86, platform, kvm, kconfig: Turn existing .config's into KVM-capable configs

x86, platform, kvm, kconfig: Turn existing .config's into KVM-capable configs

Add an config file snippet which enables additional options
useful for running the kernel in a kvm guest. When you execute
'make kvmconfig' it merges those options with an already
existing user config before you build the kernel.

Based on an patch from the external lkvm tree.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: penberg@kernel.org
Cc: levinsasha928@gmail.com
Cc: mtosatti@redhat.com
Cc: fengguang.wu@intel.com
Link: http://lkml.kernel.org/r/20130522144638.GB15085@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>