Fix 3 bugs in Avro reader/decoder, related to state handling

avro/src/main/java/tools/jackson/dataformat/avro/deser/JacksonAvroParserImpl.java

@@ -485,9 +485,10 @@ public void skipLong() throws IOException {
             int maxLeft = 9;
             int b;
             do {
-                b = _nextByteGuaranteed();
+                b = buf[ptr++];
             } while ((--maxLeft > 0) && (b < 0));
             if (b < 0) {
+                _inputPtr = ptr;
                 _reportInvalidNegative(b);
             }
         }

avro/src/main/java/tools/jackson/dataformat/avro/deser/MapReader.java

@@ -157,6 +157,7 @@ public JsonToken nextToken() throws IOException
                 _count = _parser.decodeMapNext();
                 // more stuff?
                 if (_count > 0L) {
+                    _state = STATE_VALUE;
                     _index = 0;
                     _currentName = _parser.decodeMapKey();
                     return (_currToken = JsonToken.PROPERTY_NAME);
@@ -235,6 +236,7 @@ public JsonToken nextToken() throws IOException
                 _count = _parser.decodeMapNext();
                 // more stuff?
                 if (_count > 0L) {
+                    _state = STATE_VALUE;
                     _index = 0;
                     _currentName = _parser.decodeMapKey();
                     return (_currToken = JsonToken.PROPERTY_NAME);

avro/src/main/java/tools/jackson/dataformat/avro/deser/ScalarDecoder.java

@@ -645,7 +645,7 @@ public JsonToken readValue(AvroReadContext parent, AvroParserImpl parser) throws
 
             @Override
             public void skipValue(AvroParserImpl parser) throws IOException {
-                parser.skipFloat();
+                parser.skipBytesDecimal();
             }
         }
     }