all: remove c_variadic feature

src/utils/vasprintf.rs

@@ -1,42 +0,0 @@
-use {
-    std::{
-        ffi::{CStr, VaList},
-        ops::Deref,
-        ptr,
-    },
-    uapi::c,
-};
-
-extern "C" {
-    fn vasprintf(strp: *mut *mut c::c_char, fmt: *const c::c_char, ap: VaList) -> c::c_int;
-}
-
-pub struct OwnedCStr {
-    val: &'static CStr,
-}
-
-impl Deref for OwnedCStr {
-    type Target = CStr;
-
-    fn deref(&self) -> &Self::Target {
-        self.val
-    }
-}
-
-impl Drop for OwnedCStr {
-    fn drop(&mut self) {
-        unsafe {
-            c::free(self.val.as_ptr() as _);
-        }
-    }
-}
-
-pub unsafe fn vasprintf_(fmt: *const c::c_char, ap: VaList) -> Option<OwnedCStr> {
-    let mut res = ptr::null_mut();
-    if vasprintf(&mut res, fmt, ap) == -1 {
-        return None;
-    }
-    Some(OwnedCStr {
-        val: CStr::from_ptr(res),
-    })
-}