Fixes issues with EXTINF duration conversion to microseconds

The HLS Parser converts from a string decimal duration in seconds into long
 microseconds.
Because the conversion passes through a java double type it can result in
representation errors.

For example:

`#EXTINF:4.004`  -> `Segment.durationUs` of 4003999

This matters because the first sample (which is the IDR) for a segment will be discarded following a seek because of the logic in the `SampleQueue`:

````java
    buffer.timeUs = timesUs[relativeReadIndex];
    if (buffer.timeUs < startTimeUs) {
      buffer.addFlag(C.BUFFER_FLAG_DECODE_ONLY);
    }
````

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java

@@ -48,6 +48,7 @@ import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.math.BigDecimal;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -759,8 +760,7 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
               parseStringAttr(line, REGEX_VALUE, variableDefinitions));
         }
       } else if (line.startsWith(TAG_MEDIA_DURATION)) {
-        segmentDurationUs =
+        segmentDurationUs = parseTimeSecondsToUs(line, REGEX_MEDIA_DURATION);
-            (long) (parseDoubleAttr(line, REGEX_MEDIA_DURATION) * C.MICROS_PER_SECOND);
         segmentTitle = parseOptionalStringAttr(line, REGEX_MEDIA_TITLE, "", variableDefinitions);
       } else if (line.startsWith(TAG_SKIP)) {
         int skippedSegmentCount = parseIntAttr(line, REGEX_SKIPPED_SEGMENTS);
@@ -1190,6 +1190,12 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
     return defaultValue;
   }
 
+  private static long parseTimeSecondsToUs(String line, Pattern pattern) throws ParserException {
+    String timeValueSeconds = parseStringAttr(line, pattern, Collections.emptyMap());
+    BigDecimal timeValue = new BigDecimal(timeValueSeconds);
+    return timeValue.multiply(new BigDecimal(C.MICROS_PER_SECOND)).longValue();
+  }
+
   private static double parseDoubleAttr(String line, Pattern pattern) throws ParserException {
     return Double.parseDouble(parseStringAttr(line, pattern, Collections.emptyMap()));
   }

library/hls/src/test/java/com/google/android/exoplayer2/source/hls/playlist/HlsMediaPlaylistParserTest.java

@@ -77,6 +77,9 @@ public class HlsMediaPlaylistParserTest {
             + "\n"
             + "#EXTINF:7.975,\n"
             + "https://priv.example.com/fileSequence2683.ts\n"
+            + "\n"
+            + "#EXTINF:2.002,\n"
+            + "https://priv.example.com/fileSequence2684.ts\n"
             + "#EXT-X-ENDLIST";
     InputStream inputStream = new ByteArrayInputStream(Util.getUtf8Bytes(playlistString));
     HlsPlaylist playlist = new HlsPlaylistParser().parse(playlistUri, inputStream);
@@ -93,7 +96,7 @@ public class HlsMediaPlaylistParserTest {
     assertThat(mediaPlaylist.partTargetDurationUs).isEqualTo(C.TIME_UNSET);
     List<Segment> segments = mediaPlaylist.segments;
     assertThat(segments).isNotNull();
-    assertThat(segments).hasSize(5);
+    assertThat(segments).hasSize(6);
 
     Segment segment = segments.get(0);
     assertThat(mediaPlaylist.discontinuitySequence + segment.relativeDiscontinuitySequence)
@@ -152,6 +155,9 @@ public class HlsMediaPlaylistParserTest {
     assertThat(segment.byteRangeLength).isEqualTo(C.LENGTH_UNSET);
     assertThat(segment.byteRangeOffset).isEqualTo(0);
     assertThat(segment.url).isEqualTo("https://priv.example.com/fileSequence2683.ts");
+
+    segment = segments.get(5);
+    assertThat(segment.durationUs).isEqualTo(2002000);
   }
 
   @Test