fix: support skipping entries with NO_ENTRY (-1) flag

[iBotPeaches]

fixes: #1874

In a very old (5+ year) issue. We saw a specific version of Google Hangouts failed to decode. Turns out with some fresh eyes. We just missed an important note in the spec that we should skip entries if the key/offset resolve to -1 (NO_ENTRY)

We applied that to the entry reading as well as the offset reading and it worked great to resolve what used to be this crash:

Caused by: java.io.IOException: Expected: 0x00000008, got: 0x00000202
	at brut.util.ExtDataInput.skipCheckShort(ExtDataInput.java:49)
	at brut.androlib.res.decoder.ARSCDecoder.readValue(ARSCDecoder.java:422)
	at brut.androlib.res.decoder.ARSCDecoder.readEntryData(ARSCDecoder.java:347)
	at brut.androlib.res.decoder.ARSCDecoder.readTableType(ARSCDecoder.java:326)
	at brut.androlib.res.decoder.ARSCDecoder.readResourceTable(ARSCDecoder.java:99)
	at brut.androlib.res.decoder.ARSCDecoder.decode(ARSCDecoder.java:50)