coreos-base/vboot_reference: cgpt repair command

Allow repair command to accept a whole disk or partition.
Merge pull request #950 from crawford/cgpt

coreos-base/vboot_reference: cgpt repair command
app-emulation/open-vm-tools: read passwords from shadow database
Merge pull request #946 from crawford/open-vm-tools

app-emulation/open-vm-tools: read passwords from shadow database
Merge pull request #952 from marineam/secure

Enable kernel module signing
sdk-depends: install UEFI firmware for QEMU by default

For use with the `qemu_uefi` vm type.