Speed up parse_header of the binary IndexData

The change makes a measurable performance gain for debuginfod-rs:

```
Before:
  Time (mean ± σ):      2.322 s ±  0.042 s    [User: 25.047 s, System: 4.994 s]
After:
  Time (mean ± σ):      2.269 s ±  0.023 s    [User: 24.264 s, System: 5.174 s]

1.02 ± 0.02 times faster than debuginfod-rs-before
```

src/rpm/headers/header.rs

@@ -54,13 +54,14 @@ where
  // add data to entries
  for entry in &mut entries {
  let mut remaining = &bytes[entry.offset as usize..];
+
  match &mut entry.data {
  IndexData::Null => {}
  IndexData::Char(ref mut chars) => {
- parse_entry_data_number(remaining, entry.num_items, chars, be_u8)?;
+ parse_binary_entry(remaining, entry.num_items, chars, "Char")?;
  }
  IndexData::Int8(ref mut ints) => {
- parse_entry_data_number(remaining, entry.num_items, ints, be_u8)?;
+ parse_binary_entry(remaining, entry.num_items, ints, "Int8")?;
  }
  IndexData::Int16(ref mut ints) => {
  parse_entry_data_number(remaining, entry.num_items, ints, be_u16)?;
@@ -76,7 +77,7 @@ where
  string.push_str(String::from_utf8_lossy(raw_string).as_ref());
  }
  IndexData::Bin(ref mut bin) => {
- parse_entry_data_number(remaining, entry.num_items, bin, be_u8)?;
+ parse_binary_entry(remaining, entry.num_items, bin, "Bin")?;
  }
  IndexData::StringArray(ref mut strings) => {
  for _ in 0..entry.num_items {
@@ -480,6 +481,7 @@ where
  E: nom::error::ParseError<&'a [u8]>,
  F: Fn(&'a [u8]) -> nom::IResult<&'a [u8], T, E>,
 {
+ items.reserve_exact(num_items as usize);
  for _ in 0..num_items {
  let (rest, data) = parser(input)?;
  items.push(data);
@@ -489,6 +491,22 @@ where
  Ok((input, ()))
 }
 
+fn parse_binary_entry(
+ input: &[u8],
+ num_items: u32,
+ items: &mut Vec<u8>,
+ bin_type: &str,
+) -> Result<(), Error> {
+ let bin_bytes = input.get(..num_items as usize).ok_or_else(|| {
+ Error::Nom(format!(
+ "Insufficient bytes for IndexData::{} entry",
+ bin_type
+ ))
+ })?;
+ items.extend_from_slice(bin_bytes);
+ Ok(())
+}
+
 /// A header keeping track of all other header records.
 #[derive(Debug, PartialEq)]
 pub(crate) struct IndexHeader {