ART: Clean up arm64 kNumberOfXRegisters usage.

Avoid undefined behavior for arm64 stemming from 1u << 32 in
loops with upper bound kNumberOfXRegisters.

Create iterators for enumerating bits in an integer either
from high to low or from low to high and use them for
<arch>Context::FillCalleeSaves() on all architectures.

Refactor runtime/utils.{h,cc} by moving all bit-fiddling
functions to runtime/base/bit_utils.{h,cc} (together with
the new bit iterators) and all time-related functions to
runtime/base/time_utils.{h,cc}. Improve test coverage and
fix some corner cases for the bit-fiddling functions.

Bug: 13925192

(cherry picked from commit 80afd02024d20e60b197d3adfbb43cc303cf29e0)

Change-Id: I905257a21de90b5860ebe1e39563758f721eab82
diff --git a/compiler/jit/jit_compiler.cc b/compiler/jit/jit_compiler.cc
index 7c400ee..7ed7097 100644
--- a/compiler/jit/jit_compiler.cc
+++ b/compiler/jit/jit_compiler.cc
@@ -18,6 +18,7 @@
 
 #include "arch/instruction_set.h"
 #include "arch/instruction_set_features.h"
+#include "base/time_utils.h"
 #include "base/timing_logger.h"
 #include "compiler_callbacks.h"
 #include "dex/pass_manager.h"