Add BlockHeader::clear_witness method

Author: stevenroose

src/block.rs

@@ -235,6 +235,20 @@ impl BlockHeader {
         }
     }
 
+    /// 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();
+            },
+        }
+    }
+
     /// Calculate the root of the dynafed params. Returns [None] when not dynafed.
     pub fn calculate_dynafed_params_root(&self) -> Option<sha256::Midstate> {
         match self.ext {