Change *BugReport constructors to take StringRefs.

- Eliminates many calls to std::string.c_str()
- Fixes an invalid read in ReturnStackAddressChecker due to an unsafe call to
  StringRef.data() which doesn't guarantee null-termination.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@88779 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/PointerArithChecker.cpp b/lib/Analysis/PointerArithChecker.cpp
index 5f5badb..9382348 100644
--- a/lib/Analysis/PointerArithChecker.cpp
+++ b/lib/Analysis/PointerArithChecker.cpp
@@ -59,8 +59,7 @@
                             "Pointer arithmetic done on non-array variables "
                             "means reliance on memory layout, which is "
                             "dangerous.");
-      RangedBugReport *R = new RangedBugReport(*BT,BT->getDescription().c_str(),
-                                               N);
+      RangedBugReport *R = new RangedBugReport(*BT, BT->getDescription(), N);
       R->addRange(B->getSourceRange());
       C.EmitReport(R);
     }