Match semantics of PointerMayBeCapturedBefore to its name by default

As it turns out, the capture tracker named CaptureBefore used by AA, and now
available via the PointerMayBeCapturedBefore function, would have been
more-aptly named CapturedBeforeOrAt, because it considers captures at the
instruction provided. This is not always what one wants, and it is difficult to
get the strictly-before behavior given only the current interface. This adds an
additional parameter which controls whether or not you want to include
captures at the provided instruction. The default is not to include the
instruction provided, so that 'Before' matches its name.

No functionality change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213582 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/CaptureTracking.h

@@ -40,10 +40,11 @@ namespace llvm {
   /// returning the value (or part of it) from the function counts as capturing
   /// it or not.  The boolean StoreCaptures specified whether storing the value
   /// (or part of it) into memory anywhere automatically counts as capturing it
-  /// or not.
+  /// or not. Captures by the provided instruction are considered if the
+  /// final parameter is true.
   bool PointerMayBeCapturedBefore(const Value *V, bool ReturnCaptures,
                                   bool StoreCaptures, const Instruction *I,
-                                  DominatorTree *DT);
+                                  DominatorTree *DT, bool IncludeI = false);
 
   /// This callback is used in conjunction with PointerMayBeCaptured. In
   /// addition to the interface here, you'll need to provide your own getters