Improve shootout-reverse-complement
ignore-android
Make UdpStream block until the next non-empty msg.
Deprecate UdpStream
auto merge of #18143 : mahkoh/rust/reverse_complement, r=alexcrichton

Lots of unsafe code and lots of branches removed. Also multithreaded.

Rust old: 1.208 seconds
Rust new: 0.761 seconds
C: 0.632 seconds
debuginfo: Set RUST_TEST_TASKS to 1 again for LLDB tests
auto merge of #18130 : mahkoh/rust/udp, r=alexcrichton

Closes #18111

Note that the non-empty part doesn't matter right now because of #18129.
auto merge of #18348 : michaelwoerister/rust/lldb-test-versioning, r=alexcrichton

Let's try if not running LLDB tests in parallel solves the sporadic deadlocks we've seen since enabling the LLDB test suite. Running the tests in parallel has lead to unstable behaviour in the past (with LLDB versions below 310.x.x). Maybe our new minimum LLDB version isn't quite up to it either.

cc @alexcrichton