ext4_utils: add declaration for ext4_bg_has_super_block()

Add a declaration for ext4_bg_has_super_block() so that the
encrypt-in-place code in vold can use it to determine whether a backup
superblock is present in a block group.

Bug: 162479411
Bug: 161871210
Merged-In: Ic090bf4e88193b289b04c5254ddf661ef40b037e
Change-Id: Ic090bf4e88193b289b04c5254ddf661ef40b037e
1 file changed