fix looping into readlink function when getting size of emmc partitions from link
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support custom user fstype when formatting extra storages
- start of cm-11.0, minivold has no more the options to pass fstype when formatting a voldmanaged volume
- it misses this commit from cm-10.2: https://github.com/CyanogenMod/android_system_vold/commit/6f421eeb455ae559971c1de2fdc983997b2922ca
- it will detect fstype
- if it is exfat, it will format in exfat, else, it will always default to fat
- also, ntfs and ext4 functions in minivold can no more format a device
- this temporary fix enables formatting again to user choice, bypassing minivold
- however, it needs the true blk_device, not the minivold fuse ones
- PhilZ Touch uses a simple extra.fstab parsing for this