Add support for #[deprecated].

Closes #875.
Closes #860.
Closes #408.

tests/rust/deprecated.rs

@@ -0,0 +1,52 @@
+#[no_mangle]
+#[deprecated]
+pub extern "C" fn deprecated_without_note() {}
+
+#[no_mangle]
+#[deprecated = "This is a note"]
+pub extern "C" fn deprecated_without_bracket() {}
+
+#[no_mangle]
+#[deprecated(note = "This is a note")]
+pub extern "C" fn deprecated_with_note() {}
+
+#[no_mangle]
+#[deprecated(note = "This is a note", since = "1.0.0")]
+pub extern "C" fn deprecated_with_note_and_since() {}
+
+#[no_mangle]
+#[deprecated(note = "This quote \" requires to be quoted, and this [\n] requires to be escaped")]
+pub extern "C" fn deprecated_with_note_which_requires_to_be_escaped() {}
+
+#[repr(i32)]
+#[deprecated]
+pub enum DeprecatedEnum {
+    A = 0,
+}
+
+#[repr(i32)]
+#[deprecated(note = "This is a note")]
+pub enum DeprecatedEnumWithNote {
+    B = 0,
+}
+
+#[repr(C)]
+#[deprecated]
+pub struct DeprecatedStruct {
+    pub a: i32,
+}
+
+#[repr(C)]
+#[deprecated(note = "This is a note")]
+pub struct DeprecatedStructWithNote {
+    pub a: i32,
+}
+
+#[no_mangle]
+pub extern "C" fn dummy(
+    a: DeprecatedEnum,
+    b: DeprecatedEnumWithNote,
+    c: DeprecatedStruct,
+    d: DeprecatedStructWithNote,
+) -> void {
+}

tests/rust/deprecated.toml

@@ -0,0 +1,20 @@
+header = """
+#define DEPRECATED_FUNC __attribute__((deprecated))
+#define DEPRECATED_STRUCT __attribute__((deprecated))
+#define DEPRECATED_ENUM __attribute__((deprecated))
+#define DEPRECATED_FUNC_WITH_NOTE(...) __attribute__((deprecated(__VA_ARGS__)))
+#define DEPRECATED_STRUCT_WITH_NOTE(...) __attribute__((deprecated(__VA_ARGS__)))
+#define DEPRECATED_ENUM_WITH_NOTE(...) __attribute__((deprecated(__VA_ARGS__)))
+"""
+
+[fn]
+deprecated = "DEPRECATED_FUNC"
+deprecated_with_note = "DEPRECATED_FUNC_WITH_NOTE({})"
+
+[struct]
+deprecated = "DEPRECATED_STRUCT"
+deprecated_with_note = "DEPRECATED_STRUCT_WITH_NOTE({})"
+
+[enum]
+deprecated = "DEPRECATED_ENUM"
+deprecated_with_note = "DEPRECATED_ENUM_WITH_NOTE({})"