[PATCH] [Support] Add BitHacks.h - generic bit utility functions.

[Shankar Kalpathi Easwaran]

  LGTM.


================
Comment at: include/llvm/Support/BitHacks.h:30
@@ +29,3 @@
+
+/// \brief Count number of zeros from the least significant bit to the most.
+template <typename T>
----------------
may need more documentation since this would be used as an API for lot of components.

================
Comment at: include/llvm/Support/BitHacks.h:55
@@ +54,3 @@
+
+// Disable signed.
+template <typename T>
----------------
Why disabling signed ?


http://llvm-reviews.chandlerc.com/D841