Update help message

Author: chrisvittal

Diff for: src/librustc/infer/mod.rs

@@ -97,7 +97,7 @@ impl SuppressRegionErrors {
             // If we're on Migrate mode, report AST region errors
             BorrowckMode::Migrate => SuppressRegionErrors { suppressed: false },
 
-            // If we're on MIR don't report AST region errors as they should be reported by NLL
+            // If we're on MIR, don't report AST region errors as they should be reported by NLL
             BorrowckMode::Mir => SuppressRegionErrors { suppressed: true },
         }
     }

Diff for: src/librustc/session/config.rs

@@ -1211,7 +1211,7 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
     identify_regions: bool = (false, parse_bool, [UNTRACKED],
         "make unnamed regions display as '# (where # is some non-ident unique id)"),
     borrowck: Option<String> = (None, parse_opt_string, [UNTRACKED],
-        "select which borrowck is used (`ast`, `mir`, `migrate`, or `compare`)"),
+        "select which borrowck is used (`mir` or `migrate`)"),
     time_passes: bool = (false, parse_bool, [UNTRACKED],
         "measure time of each rustc pass"),
     time: bool = (false, parse_bool, [UNTRACKED],