Make DexMerger's dex reader general purpose.

Make DexMerger's dex reader general purpose.

Use this to implement FindUsages, which prints references to
fields and methods within a dex. This is the FindUsages output
for "Ljava/lang/Number;", "longValue" on libcore's dex file:

Method referenced by Ljava/io/EmulatedFields;#get invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/io/EmulatedFieldsForDumping;#write invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/io/ObjectOutputStream;#writeFieldValues invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method declared by Ljava/lang/Number;#longValue
Method declared by Ljava/lang/Byte;#longValue
Method declared by Ljava/lang/Double;#longValue
Method declared by Ljava/lang/Float;#longValue
Method declared by Ljava/lang/Integer;#longValue
Method declared by Ljava/lang/Long;#longValue
Method declared by Ljava/lang/Short;#longValue
Method referenced by Ljava/lang/reflect/Array;#set invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/math/BigDecimal;#divideBigIntegers invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/math/BigDecimal;#divideBigIntegers invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/math/BigDecimal;#divideBigIntegers invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/math/BigDecimal;#readObject invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/math/BigDecimal;#setUnscaledValue invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/math/BigDecimal;#valueExact invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/math/BigDecimal;#doubleValue invoke-virtual/range {vCCCC..vNNNN}, meth@BBBB
Method referenced by Ljava/math/BigDecimal;#doubleValue invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method declared by Ljava/math/BigDecimal;#longValue
Method referenced by Ljava/math/BigDecimal;#longValue invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method declared by Ljava/math/BigInteger;#longValue
Method referenced by Ljava/math/Conversion;#bigInteger2Double invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/math/Conversion;#bigInteger2Double invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/text/NumberFormat;#format invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/text/DateFormat;#format invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/text/DecimalFormat;#format invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/text/DecimalFormat;#parse invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/text/SimpleDateFormat;#formatToCharacterIterator invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transform invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transformFromDateTime invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transformFromInteger invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transformFromInteger invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transformFromInteger invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transformFromInteger invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transform_g invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transform_g invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transform_g invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Formatter;#transform_g invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Ljava/util/Scanner;#nextLong invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method declared by Ljava/util/concurrent/atomic/AtomicInteger;#longValue
Method declared by Ljava/util/concurrent/atomic/AtomicLong;#longValue
Method referenced by Llibcore/icu/NativeDecimalFormat;#formatToCharacterIterator invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/apache/xalan/xslt/SecuritySupport12;#getLastModified invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/apache/xml/dtm/SecuritySupport12;#getLastModified invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/apache/xml/dtm/ref/SecuritySupport12;#getLastModified invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/apache/xml/serializer/SecuritySupport12;#getLastModified invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/apache/xml/utils/SecuritySupport12;#getLastModified invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/apache/xpath/functions/SecuritySupport12;#getLastModified invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/json/JSON;#toLong invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/json/JSONArray;#getLong invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/json/JSONArray;#optLong invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/json/JSONObject;#numberToString invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/json/JSONObject;#getLong invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC
Method referenced by Lorg/json/JSONObject;#optLong invoke-virtual {vD, vE, vF, vG, vA}, meth@CCCC

Change-Id: Ia50f28f53ce5838799e2d5f03a7a2f1c551299de