Fix endian-neutral parsers that use attributes

[cky]

Normally, when using the Nom derive, parse_le delegates to parse_le, and parse_be delegates to parse_be. This allows the parser to be endian-neutral.

However, when using attributes, this is no longer the case, and both parse_le and parse_be delegate to parse. For example, for the below struct, MyStruct::parse_le and MyStruct::parse_be will both parse the u32 as big-endian:

#[derive(Nom)]
struct MyStruct(#[nom(Complete)] u32);

[cky]

By the way, when running tests locally, it seems that the compiler output has changed for the current version, breaking some of the compile-fail tests. Here's a diff to fix those:

diff --git a/tests/compile-fail/error-enums.stderr b/tests/compile-fail/error-enums.stderr
index 4488c9f..ddc3731 100644
--- a/tests/compile-fail/error-enums.stderr
+++ b/tests/compile-fail/error-enums.stderr
@@ -27,3 +27,5 @@ error[E0552]: unrecognized representation hint
    |
 27 | #[repr(U24)] // ERROR: Nom-derive: cannot parse 'repr' content (must be a primitive type)
    |        ^^^
+   |
+   = help: valid reprs are `C`, `align`, `packed`, `transparent`, `simd`, `i8`, `u8`, `i16`, `u16`, `i32`, `u32`, `i64`, `u64`, `i128`, `u128`, `isize`, `usize`
diff --git a/tests/compile-fail/unsupported_types.stderr b/tests/compile-fail/unsupported_types.stderr
index 3a5a5d6..a15cc01 100644
--- a/tests/compile-fail/unsupported_types.stderr
+++ b/tests/compile-fail/unsupported_types.stderr
@@ -2,7 +2,7 @@ error: Nom-derive: multiple segments in type path are not supported
   --> $DIR/unsupported_types.rs:14:8
    |
 14 |     h: ::std::primitive::u64, // ERROR: Nom-derive: multiple segments in type path are not supported
-   |        ^^
+   |        ^
 
 error[E0599]: no function or associated item named `parse_be` found for struct `HashMap` in the current scope
  --> $DIR/unsupported_types.rs:7:10