Add C-lightning v0.8.1

[darosior]

This builds upon https://github.com/greenaddress/bitcoin_ndk/pull/21 and updates the patches to build the last C-lightning release, v0.8.1.

There might be a more elegant solution than ae85c60a0cab66ebb0f2a0acd18da72301ca70c9, which grossly reverts two commits.

Anyway thanks a lot for the initial port of C-lightning !

[darosior]

(amended the first commit as I forgot to delete a patchfile..)

[lvaccaro]

ack 10f4b78e3aad05e05b512517a4fc3ea636170f76

Cross-compiled binaries works well on android device, I still add a bunch of commits on top to fix my local building process and add bcli plugin on local https://github.com/lvaccaro/bitcoin_ndk/tree/add_clightningv0.8.1 .