We support file-based encryption on both ext4 and f2fs now, and the
kernel API is the same. So rename things appropriately in vold:
e4crypt => fscrypt
ext4enc => fscrypt
Ext4Crypt => FsCrypt
EXT4_* => FS_*
ext4_encryption_key => fscrypt_key
Additionally, the common functions shared by 'vold' and 'init' are now
in libfscrypt rather than ext4_utils. So update vold to link to
libfscrypt and include the renamed headers.
Note: there's a chance of 'fscrypt' being confused with the dm-crypt
based encryption code in vold which is called 'cryptfs'. However,
fscrypt is the name used in the kernel for ext4/f2fs/ubifs encryption,
and it's preferable to use the same name in userspace.
Test: built, booted device with f2fs encryption
Change-Id: I2a46a49f30d9c0b73d6f6fe09e4a4904d4138ff6
