Remove the seek_stream_len feature flag.

Author: sunfishcode

build.rs

@@ -9,7 +9,6 @@ fn main() {
             "extend_one",         // https://github.com/rust-lang/rust/issues/72631
             "pattern",            // https://github.com/rust-lang/rust/issues/27721
             "seek_convenience",   // https://github.com/rust-lang/rust/issues/59359
-            "seek_stream_len ",   // https://github.com/rust-lang/rust/issues/59359
             "shrink_to",          // https://github.com/rust-lang/rust/issues/56431
             "toowned_clone_into", // https://github.com/rust-lang/rust/issues/41263
             "try_reserve",        // https://github.com/rust-lang/rust/issues/56431

cap-fs-ext/build.rs

@@ -9,7 +9,6 @@ fn main() {
             "extend_one",         // https://github.com/rust-lang/rust/issues/72631
             "pattern",            // https://github.com/rust-lang/rust/issues/27721
             "seek_convenience",   // https://github.com/rust-lang/rust/issues/59359
-            "seek_stream_len ",   // https://github.com/rust-lang/rust/issues/59359
             "shrink_to",          // https://github.com/rust-lang/rust/issues/56431
             "toowned_clone_into", // https://github.com/rust-lang/rust/issues/41263
             "try_reserve",        // https://github.com/rust-lang/rust/issues/56431

cap-primitives/build.rs

@@ -9,7 +9,6 @@ fn main() {
             "extend_one",         // https://github.com/rust-lang/rust/issues/72631
             "pattern",            // https://github.com/rust-lang/rust/issues/27721
             "seek_convenience",   // https://github.com/rust-lang/rust/issues/59359
-            "seek_stream_len",    // https://github.com/rust-lang/rust/issues/59359
             "shrink_to",          // https://github.com/rust-lang/rust/issues/56431
             "toowned_clone_into", // https://github.com/rust-lang/rust/issues/41263
             "try_reserve",        // https://github.com/rust-lang/rust/issues/56431

cap-std/build.rs

@@ -9,7 +9,6 @@ fn main() {
             "extend_one",         // https://github.com/rust-lang/rust/issues/72631
             "pattern",            // https://github.com/rust-lang/rust/issues/27721
             "seek_convenience",   // https://github.com/rust-lang/rust/issues/59359
-            "seek_stream_len",    // https://github.com/rust-lang/rust/issues/59359
             "shrink_to",          // https://github.com/rust-lang/rust/issues/56431
             "toowned_clone_into", // https://github.com/rust-lang/rust/issues/41263
             "try_reserve",        // https://github.com/rust-lang/rust/issues/56431

cap-std/src/lib.rs

@@ -27,7 +27,6 @@
 #![cfg_attr(target_os = "wasi", feature(wasi_ext))]
 #![cfg_attr(can_vector, feature(can_vector))]
 #![cfg_attr(seek_convenience, feature(seek_convenience))]
-#![cfg_attr(seek_stream_len, feature(seek_stream_len))]
 #![cfg_attr(with_options, feature(with_options))]
 #![cfg_attr(write_all_vectored, feature(write_all_vectored))]
 #![doc(