Combine terminal variants

We have various variants in this pattern that return the same thing, we
can combine them to make the code more terse with no loss of clarity.

Author: tcharding

src/miniscript/satisfy.rs

@@ -1332,15 +1332,11 @@ impl Satisfaction {
                 stack: Witness::empty(),
                 has_sig: false,
             },
-            Terminal::True => Satisfaction {
-                stack: Witness::Impossible,
-                has_sig: false,
-            },
-            Terminal::Older(_) => Satisfaction {
-                stack: Witness::Impossible,
-                has_sig: false,
-            },
-            Terminal::After(_) => Satisfaction {
+            Terminal::True
+            | Terminal::Older(_)
+            | Terminal::After(_)
+            | Terminal::Verify(_)
+            | Terminal::OrC(..) => Satisfaction {
                 stack: Witness::Impossible,
                 has_sig: false,
             },
@@ -1361,10 +1357,6 @@ impl Satisfaction {
                 stack: Witness::push_0(),
                 has_sig: false,
             },
-            Terminal::Verify(_) => Satisfaction {
-                stack: Witness::Impossible,
-                has_sig: false,
-            },
             Terminal::AndV(ref v, ref other) => {
                 let vsat =
                     Self::satisfy_helper(&v.node, stfr, root_has_sig, leaf_hash, min_fn, thresh_fn);
@@ -1406,10 +1398,6 @@ impl Satisfaction {
                     has_sig: rnsat.has_sig || lnsat.has_sig,
                 }
             }
-            Terminal::OrC(..) => Satisfaction {
-                stack: Witness::Impossible,
-                has_sig: false,
-            },
             Terminal::OrI(ref l, ref r) => {
                 let lnsat = Self::dissatisfy_helper(
                     &l.node,