P31xx: Preload libjhead in init

Older camera HALs call on libexif, and with the name change to libjhead here:
https://android.googlesource.com/platform/external/jhead/+/acbfc9c1c7e1a84b0db4dc5bc3d5346b6c55c473

It cannot find the necessary functions/symbols. Loading libjhead before any other libraries
solves this problem nicely.

Thanks to arcee for advice on the fix!

Change-Id: I93c9423e5ac18df85787b058273fef1503e0aa14