Adding binary hprof support to SamplingProfiler

SamplingProfiler refactored:
- HprofData is now a separate class, the common data structure
- SamplingProfiler uses HprofData as its runtime format
- AsciiHprofWriter refactored from profiler, takes an HprofData
- new BinaryHprofWriter to output HprofData in binary format
- new BinaryHprofReader can recreate HprofData from binary file
- new HprofBinaryToAscii command line tool to convert formats

	dalvik/src/main/java/dalvik/system/SamplingProfiler.java

SamplingProfilerTest expanded to cover new HprofData class
directly. Includes testing of conversion from various hand constructed
HprofData to ascii and binary formats as well as from binary back to
HprofData with out loss of data.

	dalvik/src/test/java/dalvik/system/SamplingProfilerTest.java

Change-Id: I6fe06f5dbdbf2f0bf2de228d9761f84d75290ba7