Fix Mips64 utils.h typo

Include of art's utils.h was mistyped as util.h, and instead
brought in external/icu/icu4c/source/common/util.h,
which caused art build failures from -Wdeprecated warnings
when Mips64 libart is compiled with clang.

Change-Id: I9370c4dc041eaecc5d5a1490ec23034ece4322a9