from Peter Gregus:

    Added support for boot and recovery partitions backup

    EMMC of MTK6589 is a large continuous block covering
    all partitions. Recovery and boot partitions definitions are
    somewhat hidden from MBR and /proc/emmc disabling CWM
    to determine correct sizes of these partitions automatically.
    This results in CWM using standard fseek/ftell method which
    returns the size of the whole EMMC which can be several Gigabytes.

    This commit enables to define sizes for boot and recovery partitions
    explicitly using BoardConfig flags - so the correct number of bytes
    can be copied from these devices during backup.

    Two pairs of config flags are available:
    CWM_EMMC_BOOT_DEVICE_NAME: defines the name of boot partition device
    (typically /dev/bootimg)
    CWM_EMMC_BOOT_DEVICE_SIZE: defines size of boot partition in bytes

    CWM_EMMC_RECOVERY_DEVICE_NAME: defines the name of recovery partition device
    (typically /dev/recovery)
    CWM_EMMC_RECOVERY_DEVICE_SIZE: defines size of recovery partition in bytes

    During backup, the name of partition being processed is checked against
    defined *DEVICE_NAME flag. If matches then size is set from the corresponding
    *DEVICE_SIZE flag.

Change-Id: I57a91b67679c6f0bd9a6d70ce5db0093ee2adb4a