Add BlockHeader::clear_witness method

Author: stevenroose

src/block.rs

@@ -234,6 +234,20 @@ impl BlockHeader {
             false
         }
     }
+
+    /// Remove the witness data of the block header.
+    /// This is all the data that can be removed without changing
+    /// the block hash.
+    pub fn clear_witness(&mut self) {
+        match &mut self.ext {
+            &mut ExtData::Proof { ref mut solution, .. } => {
+                *solution = Script::new();
+            },
+            &mut ExtData::Dynafed { ref mut signblock_witness, .. } => {
+                signblock_witness.clear();
+            },
+        }
+    }
 }
 
 impl Encodable for BlockHeader {