fixup! channeld: Code to implement splicing

Test case fixes for s64

Author: ddustin

contrib/pyln-proto/tests/test_fundamental_types.py

@@ -13,6 +13,9 @@ def test_fundamental_types():
               'u64': [['18446744073709551615',
                        b'\xff\xff\xff\xff\xff\xff\xff\xff'],
                       ['0', b'\x00\x00\x00\x00\x00\x00\x00\x00']],
+              's64': [['-1',
+                       b'\xff\xff\xff\xff\xff\xff\xff\xff'],
+                      ['0', b'\x00\x00\x00\x00\x00\x00\x00\x00']],
               'tu16': [['65535', b'\xff\xff'],
                        ['256', b'\x01\x00'],
                        ['255', b'\xff'],