ANDROID: Add initial x86_64 gki_defconfig

That is a copy from the aarch64 gki_defconfig.

To be able to build in this configuration,

    + CONFIG_UNWINDER_FRAME_POINTER=y

was necessary.

Bug: 132113225
Bug: 132629930
Change-Id: I685ccea29efc7ba14f7b0a24f41983e37203f9a2
Signed-off-by: Ram Muthiah <rammuthiah@google.com>
Signed-off-by: Matthias Maennich <maennich@google.com>