Auto merge of #28900 - cristicbz:typos, r=alexcrichton

I found these automatically, but fixed them manually to ensure the semantics are correct. I know things like these are hardly important, since they only marginally improve clarity. But at least for me typos and simple grammatical errors trigger an---unjustified---sense of unprofessionalism, despite the fact that I make them all the time and I understand that they're the sort of thing that is bound to slip through review.  

Anyway, to find most of these I used:

  * `ag '.*//.*(\b[A-Za-z]{2,}\b) \1\b'` for repeated words

  * `ag '\b(the|this|those|these|a|it) (a|the|this|those|these|it)\b'` to find constructs like 'the this' etc. many false positives, but not too hard to scroll through them to actually find the mistakes.

  * `cat ../../typos.txt | paste -d'|' - - - - - - - - - - - - - - - - - - - - - - | tr '\n' '\0' | xargs -0 -P4 -n1 ag`. Hacky way to find misspellings, but it works ok. I got `typos.txt` from [Wikipedia](https://en.wikipedia.org/wiki/Wikipedia:Lists_of_common_misspellings/For_machines)

* `ag '.*//.* a ([ae][a-z]|(o[^n])|(i[a-rt-z]))'` to find places where 'a' was followed by a vowel (requiring 'an' instead).

I also used a handful more one off regexes that are too boring to reproduce here.

2 files changed, 3 insertions, 3 deletions

diff --git a/src/libstd/sys/windows/mod.rs b/src/libstd/sys/windows/mod.rs
index 04bb5e5ea38..85f5d4e5884 100644
--- a/src/libstd/sys/windows/mod.rs
+++ b/src/libstd/sys/windows/mod.rs
@@ -75,8 +75,8 @@ fn to_utf16_os(s: &OsStr) -> Vec<u16> {
     v
 }
 
-// Many Windows APIs follow a pattern of where we hand the a buffer and then
-// they will report back to us how large the buffer should be or how many bytes
+// Many Windows APIs follow a pattern of where we hand a buffer and then they
+// will report back to us how large the buffer should be or how many bytes
 // currently reside in the buffer. This function is an abstraction over these
 // functions by making them easier to call.
 //
diff --git a/src/libstd/sys/windows/mutex.rs b/src/libstd/sys/windows/mutex.rs
index 277c3d14c0e..b770156582d 100644
--- a/src/libstd/sys/windows/mutex.rs
+++ b/src/libstd/sys/windows/mutex.rs
@@ -22,7 +22,7 @@
 //!    more details.
 //!
 //! 3. While CriticalSection is fair and SRWLock is not, the current Rust policy
-//!    is there there are no guarantees of fairness.
+//!    is that there are no guarantees of fairness.
 //!
 //! The downside of this approach, however, is that SRWLock is not available on
 //! Windows XP, so we continue to have a fallback implementation where