Revert "Fix ABI compatibility with Emscripten >= 3.1.42"

This reverts commit 63b0d67,
now that Rust requires Emscripten 3.1.42 or later.

Author: kleisauke

build.rs

@@ -6,7 +6,6 @@ use std::str;
 // need to know all the possible cfgs that this script will set. If you need to set another cfg
 // make sure to add it to this list as well.
 const ALLOWED_CFGS: &'static [&'static str] = &[
-    "emscripten_new_stat_abi",
     "espidf_time32",
     "freebsd10",
     "freebsd11",
@@ -67,12 +66,6 @@ fn main() {
         _ => set_cfg("freebsd15"),
     }
 
-    match emcc_version_code() {
-        Some(v) if (v >= 30142) => set_cfg("emscripten_new_stat_abi"),
-        // Non-Emscripten or version < 3.1.42.
-        Some(_) | None => (),
-    }
-
     // On CI: deny all warnings
     if libc_ci {
         set_cfg("libc_deny_warnings");
@@ -212,28 +205,6 @@ fn which_freebsd() -> Option<i32> {
     }
 }
 
-fn emcc_version_code() -> Option<u64> {
-    let output = std::process::Command::new("emcc")
-        .arg("-dumpversion")
-        .output()
-        .ok()?;
-    if !output.status.success() {
-        return None;
-    }
-
-    let version = String::from_utf8(output.stdout).ok()?;
-
-    // Some Emscripten versions come with `-git` attached, so split the
-    // version string also on the `-` char.
-    let mut pieces = version.trim().split(['.', '-']);
-
-    let major = pieces.next().and_then(|x| x.parse().ok()).unwrap_or(0);
-    let minor = pieces.next().and_then(|x| x.parse().ok()).unwrap_or(0);
-    let patch = pieces.next().and_then(|x| x.parse().ok()).unwrap_or(0);
-
-    Some(major * 10000 + minor * 100 + patch)
-}
-
 fn set_cfg(cfg: &str) {
     if !ALLOWED_CFGS.contains(&cfg) {
         panic!("trying to set cfg {}, but it is not in ALLOWED_CFGS", cfg);

src/unix/linux_like/emscripten/mod.rs

@@ -230,17 +230,11 @@ s! {
     }
     pub struct stat {
         pub st_dev: ::dev_t,
-        #[cfg(not(emscripten_new_stat_abi))]
-        __st_dev_padding: ::c_int,
-        #[cfg(not(emscripten_new_stat_abi))]
-        __st_ino_truncated: ::c_long,
         pub st_mode: ::mode_t,
         pub st_nlink: ::nlink_t,
         pub st_uid: ::uid_t,
         pub st_gid: ::gid_t,
         pub st_rdev: ::dev_t,
-        #[cfg(not(emscripten_new_stat_abi))]
-        __st_rdev_padding: ::c_int,
         pub st_size: ::off_t,
         pub st_blksize: ::blksize_t,
         pub st_blocks: ::blkcnt_t,