Use common type alias for anonymous enums in consts mode

Previously, anonymous enums generated a type alias but did not use it.
For example the following:

```C
enum {
    ZERO,
    ONE = 4999,
};
```

Generated this:

```Rust
/* automatically generated by rust-bindgen 0.59.2 */

pub const ZERO: ::std::os::raw::c_uint = 0;
pub const ONE: ::std::os::raw::c_uint = 4999;
pub type _bindgen_ty_1 = ::std::os::raw::c_uint;
```

For use cases where humans look at bindgen's Rust output this was a little
strange since it's a deviation from how the Rust output for named enums
is organized, where all constants share the same type using the type
alias. The unused type alias also triggered the dead_code lint.

Change to use the generated type alias.

4 files changed, 9 insertions, 9 deletions

diff --git a/tests/expectations/tests/enum-default-consts.rs b/tests/expectations/tests/enum-default-consts.rs
index 5c023a3c..d7f5d7c2 100644
--- a/tests/expectations/tests/enum-default-consts.rs
+++ b/tests/expectations/tests/enum-default-consts.rs
@@ -10,8 +10,8 @@
 pub struct foo {
     pub member: foo__bindgen_ty_1,
 }
-pub const foo_FOO_A: ::std::os::raw::c_uint = 0;
-pub const foo_FOO_B: ::std::os::raw::c_uint = 1;
+pub const foo_FOO_A: foo__bindgen_ty_1 = 0;
+pub const foo_FOO_B: foo__bindgen_ty_1 = 1;
 pub type foo__bindgen_ty_1 = ::std::os::raw::c_uint;
 #[test]
 fn bindgen_test_layout_foo() {
@@ -60,4 +60,4 @@ pub type NoDebug = ::std::os::raw::c_uint;
 pub const Debug_Debug1: Debug = 0;
 pub const Debug_Debug2: Debug = 1;
 /// <div rustbindgen derive="Debug"></div>
-pub type Debug = ::std::os::raw::c_uint;
\ No newline at end of file
+pub type Debug = ::std::os::raw::c_uint;
diff --git a/tests/expectations/tests/enum.rs b/tests/expectations/tests/enum.rs
index cc3f4932..fd76151f 100644
--- a/tests/expectations/tests/enum.rs
+++ b/tests/expectations/tests/enum.rs
@@ -10,8 +10,8 @@
 pub struct foo {
     pub member: foo__bindgen_ty_1,
 }
-pub const foo_FOO_A: ::std::os::raw::c_uint = 0;
-pub const foo_FOO_B: ::std::os::raw::c_uint = 1;
+pub const foo_FOO_A: foo__bindgen_ty_1 = 0;
+pub const foo_FOO_B: foo__bindgen_ty_1 = 1;
 pub type foo__bindgen_ty_1 = ::std::os::raw::c_uint;
 #[test]
 fn bindgen_test_layout_foo() {
@@ -58,4 +58,4 @@ pub type NoDebug = ::std::os::raw::c_uint;
 pub const Debug_Debug1: Debug = 0;
 pub const Debug_Debug2: Debug = 1;
 /// <div rustbindgen derive="Debug"></div>
-pub type Debug = ::std::os::raw::c_uint;
\ No newline at end of file
+pub type Debug = ::std::os::raw::c_uint;
diff --git a/tests/expectations/tests/enum_explicit_type_constants.rs b/tests/expectations/tests/enum_explicit_type_constants.rs
index 117f6847..0c833b66 100644
--- a/tests/expectations/tests/enum_explicit_type_constants.rs
+++ b/tests/expectations/tests/enum_explicit_type_constants.rs
@@ -26,6 +26,6 @@ pub type BoolEnumsAreFun = bool;
 pub type MyType = bool;
 pub const BoolEnumsAreFun2_Value2: BoolEnumsAreFun2 = true;
 pub type BoolEnumsAreFun2 = MyType;
-pub const AnonymousVariantOne: ::std::os::raw::c_uchar = 0;
-pub const AnonymousVariantTwo: ::std::os::raw::c_uchar = 1;
+pub const AnonymousVariantOne: _bindgen_ty_1 = 0;
+pub const AnonymousVariantTwo: _bindgen_ty_1 = 1;
 pub type _bindgen_ty_1 = ::std::os::raw::c_uchar;
diff --git a/tests/expectations/tests/parsecb-anonymous-enum-variant-rename.rs b/tests/expectations/tests/parsecb-anonymous-enum-variant-rename.rs
index e615486e..8ead5b8a 100644
--- a/tests/expectations/tests/parsecb-anonymous-enum-variant-rename.rs
+++ b/tests/expectations/tests/parsecb-anonymous-enum-variant-rename.rs
@@ -5,5 +5,5 @@
     non_upper_case_globals
 )]
 
-pub const RENAMED_MyVal: ::std::os::raw::c_uint = 0;
+pub const RENAMED_MyVal: _bindgen_ty_1 = 0;
 pub type _bindgen_ty_1 = ::std::os::raw::c_uint;