emscripten: Remove aio.h usage

See: emscripten-core/emscripten@6416c35.

(backport <rust-lang#3962>)
(cherry picked from commit 01c72ee)

libc-test/build.rs

@@ -2794,7 +2794,6 @@ fn test_emscripten(target: &str) {
     cfg.define("_GNU_SOURCE", None); // FIXME: ??
 
     headers! { cfg:
-               "aio.h",
                "ctype.h",
                "dirent.h",
                "dlfcn.h",
@@ -3019,10 +3018,7 @@ fn test_emscripten(target: &str) {
         (struct_ == "sigaction" && field == "sa_sigaction") ||
         // sigval is actually a union, but we pretend it's a struct
         // FIXME: is this necessary?
-        (struct_ == "sigevent" && field == "sigev_value") ||
-        // aio_buf is "volatile void*" and Rust doesn't understand volatile
-        // FIXME: is this necessary?
-        (struct_ == "aiocb" && field == "aio_buf")
+        (struct_ == "sigevent" && field == "sigev_value")
     });
 
     cfg.skip_field(move |struct_, field| {

src/unix/linux_like/emscripten/mod.rs

@@ -171,23 +171,6 @@ s! {
         pub sem_flg: ::c_short,
     }
 
-    pub struct aiocb {
-        pub aio_fildes: ::c_int,
-        pub aio_lio_opcode: ::c_int,
-        pub aio_reqprio: ::c_int,
-        pub aio_buf: *mut ::c_void,
-        pub aio_nbytes: ::size_t,
-        pub aio_sigevent: ::sigevent,
-        __td: *mut ::c_void,
-        __lock: [::c_int; 2],
-        __err: ::c_int,
-        __ret: ::ssize_t,
-        pub aio_offset: off_t,
-        __next: *mut ::c_void,
-        __prev: *mut ::c_void,
-        __dummy4: [::c_char; 24],
-    }
-
     pub struct sigaction {
         pub sa_sigaction: ::sighandler_t,
         pub sa_mask: ::sigset_t,
@@ -917,15 +900,6 @@ pub const SYNC_FILE_RANGE_WAIT_AFTER: ::c_uint = 4;
 
 pub const EAI_SYSTEM: ::c_int = -11;
 
-pub const AIO_CANCELED: ::c_int = 0;
-pub const AIO_NOTCANCELED: ::c_int = 1;
-pub const AIO_ALLDONE: ::c_int = 2;
-pub const LIO_READ: ::c_int = 0;
-pub const LIO_WRITE: ::c_int = 1;
-pub const LIO_NOP: ::c_int = 2;
-pub const LIO_WAIT: ::c_int = 0;
-pub const LIO_NOWAIT: ::c_int = 1;
-
 pub const MREMAP_MAYMOVE: ::c_int = 1;
 pub const MREMAP_FIXED: ::c_int = 2;