[infer][PR] small typo fix

Summary: Closes https://github.com/facebook/infer/pull/598

Differential Revision: D4642709

Pulled By: jvillard

fbshipit-source-id: 6999405

infer/src/IR/Exceptions.ml

@@ -335,7 +335,7 @@ let err_class_string = function
   | Nocat -> ""
   | Linters -> "Linters"
 
-(** wether to print the bug key together with the error message *)
+(** whether to print the bug key together with the error message *)
 let print_key = false
 
 (** pretty print an error given its (id,key), location, kind, name, description, and optional ml location *)