hwc : Compilation issue fix.

    Added unsed-paramter to C_FLAGS
    Removed page.h
    Included sync.h

Change-Id: I86db10f108132a7ebc7d4d56be4c18a6ad5017f7
display-legacy: turn off Werror...again

Change-Id: I2c63495ccba924b7e78753725431ff9586d72f45