Fix a ton of comment typos found by codespell.  Patch by
Luis Felipe Strano Moraes!

llvm-svn: 129558
diff --git a/llvm/lib/Support/PrettyStackTrace.cpp b/llvm/lib/Support/PrettyStackTrace.cpp
index a9f4709..082b701 100644
--- a/llvm/lib/Support/PrettyStackTrace.cpp
+++ b/llvm/lib/Support/PrettyStackTrace.cpp
@@ -8,7 +8,7 @@
 //===----------------------------------------------------------------------===//
 //
 // This file defines some helpful functions for dealing with the possibility of
-// Unix signals occuring while your program is running.
+// Unix signals occurring while your program is running.
 //
 //===----------------------------------------------------------------------===//