Remove redundant closures

Clippy emits a bunch of warnings of form:

  warning: redundant closure

As suggested, remove the redundant closures and just pass in the
function.

Author: tcharding

src/descriptor/key.rs

@@ -562,7 +562,7 @@ impl<K: InnerXKey> DescriptorXKey<K> {
                 DescriptorKeyParseError("Malformed master fingerprint, expected 8 hex chars")
             })?;
             let origin_path = raw_origin
-                .map(|p| bip32::ChildNumber::from_str(p))
+                .map(bip32::ChildNumber::from_str)
                 .collect::<Result<bip32::DerivationPath, bip32::Error>>()
                 .map_err(|_| {
                     DescriptorKeyParseError("Error while parsing master derivation path")

src/interpreter/inner.rs

@@ -233,8 +233,8 @@ pub(super) fn from_txdata<'txin>(
                     let ctrl_blk = wit_stack.pop().ok_or(Error::UnexpectedStackEnd)?;
                     let ctrl_blk = ctrl_blk.as_push()?;
                     let tap_script = wit_stack.pop().ok_or(Error::UnexpectedStackEnd)?;
-                    let ctrl_blk = ControlBlock::from_slice(ctrl_blk)
-                        .map_err(|e| Error::ControlBlockParse(e))?;
+                    let ctrl_blk =
+                        ControlBlock::from_slice(ctrl_blk).map_err(Error::ControlBlockParse)?;
                     let tap_script = script_from_stackelem::<Tap>(&tap_script)?;
                     let ms = tap_script.to_no_checks_ms();
                     // Creating new contexts is cheap

src/miniscript/astelem.rs

@@ -555,7 +555,7 @@ where
 
                 let subs: Result<Vec<Arc<Miniscript<Pk, Ctx>>>, _> = top.args[1..]
                     .iter()
-                    .map(|sub| expression::FromTree::from_tree(sub))
+                    .map(expression::FromTree::from_tree)
                     .collect();
 
                 Ok(Terminal::Thresh(k, subs?))

src/policy/concrete.rs

@@ -571,7 +571,7 @@ where
             ("TRIVIAL", 0) => Ok(Policy::Trivial),
             ("pk", 1) => expression::terminal(&top.args[0], |pk| Pk::from_str(pk).map(Policy::Key)),
             ("after", 1) => {
-                let num = expression::terminal(&top.args[0], |x| expression::parse_num(x))?;
+                let num = expression::terminal(&top.args[0], expression::parse_num)?;
                 if num > 2u32.pow(31) {
                     return Err(Error::PolicyError(PolicyError::TimeTooFar));
                 } else if num == 0 {
@@ -580,7 +580,7 @@ where
                 Ok(Policy::After(num))
             }
             ("older", 1) => {
-                let num = expression::terminal(&top.args[0], |x| expression::parse_num(x))?;
+                let num = expression::terminal(&top.args[0], expression::parse_num)?;
                 if num > 2u32.pow(31) {
                     return Err(Error::PolicyError(PolicyError::TimeTooFar));
                 } else if num == 0 {