Remove long-outdated QUESTIONS.md

This is quite an old file now at this point!

library/stdarch/QUESTIONS.md

@@ -1,31 +0,0 @@
-This program emits `psllw` instead of `pslliw` instruction. `pslliw` should be
-usable here since `imm8` is a constant:
-
-```rust
-extern crate stdarch;
-
-use std::env;
-use stdarch as s;
-
-fn main() {
-    let imm8: i32 = env::args().nth(1).unwrap().parse().unwrap();
-    let a = s::i16x8::new(imm8 as i16, 0, 0, 0, 0, 0, 0, 0);
-    println!("{:?}", s::_mm_slli_epi16(a, 4));
-}
-```
-
----
-
-LLVM types the `count` parameter in `_mm_sll_epi16` as `i16x8`, but the right
-type is probably `i64x2`.
-
----
-
-What is the deal with the ucomi f64 comparison functions in SSE2? Clang's
-headers indicate some specific behavior with NAN, but I can't seem to reproduce
-it. Intel's official docs are very vague.
-
----
-
-`_mm256_blendv_pd` takes a mask parameter with type `f64x4`, but the
-documentation seems to indicate that it is a bit vector. What's going on?