Use bitcheck to check for presence of OPT_FULL option

Previously an equality check was performed so an exception would
be thrown if any other options were set.

Change-Id: I36b60e2c0a8aef9fcfe663055dba520192996872

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexV1.java

@@ -110,15 +110,10 @@ class PackBitmapIndexV1 extends BasePackBitmapIndex {
 
 		// Read the options (2 bytes)
 		final int opts = NB.decodeUInt16(scratch, 6);
-		switch (opts) {
-		case OPT_FULL:
-			// Bitmaps are self contained within this file.
-			break;
-		default:
+		if ((opts & OPT_FULL) == 0)
 			throw new IOException(MessageFormat.format(
 					JGitText.get().expectedGot, Integer.valueOf(OPT_FULL),
 					Integer.valueOf(opts)));
-		}
 
 		// Read the number of entries (1 int32)
 		long numEntries = NB.decodeUInt32(scratch, 8);