Remove double spaces after dots in comments

compiler/rustc_error_codes/src/error_codes.rs

@@ -1,5 +1,5 @@
-// Error messages for EXXXX errors.  Each message should start and end with a
-// new line, and be wrapped to 80 characters.  In vim you can `:set tw=80` and
+// Error messages for EXXXX errors. Each message should start and end with a
+// new line, and be wrapped to 80 characters. In vim you can `:set tw=80` and
 // use `gq` to wrap paragraphs. Use `:set tw=0` to disable.
 //
 // /!\ IMPORTANT /!\

compiler/rustc_error_codes/src/error_codes/E0387.md

@@ -17,7 +17,7 @@ fn mutable() {
     foo(|| x = 2);
 }
 
-// Attempts to take a mutable reference to closed-over data.  Error message
+// Attempts to take a mutable reference to closed-over data. Error message
 // reads: `cannot borrow data mutably in a captured outer variable...`
 fn mut_addr() {
     let mut x = 0u32;

compiler/rustc_error_codes/src/error_codes/E0713.md

@@ -22,7 +22,7 @@ gets called when they go out of scope. This destructor gets exclusive
 access to the fields of the struct when it runs.
 
 This means that when `s` reaches the end of `demo`, its destructor
-gets exclusive access to its `&mut`-borrowed string data.  allowing
+gets exclusive access to its `&mut`-borrowed string data. allowing
 another borrow of that string data (`p`), to exist across the drop of
 `s` would be a violation of the principle that `&mut`-borrows have
 exclusive, unaliased access to their referenced data.

compiler/rustc_error_codes/src/error_codes/E0714.md

@@ -15,5 +15,5 @@ fn main() {}
 ```
 
 The items of marker traits cannot be overridden, so there's no need to have them
-when they cannot be changed per-type anyway.  If you wanted them for ergonomic
+when they cannot be changed per-type anyway. If you wanted them for ergonomic
 reasons, consider making an extension trait instead.