[findBugs] Prefer short-cut logic as it's more performant

Change-Id: I64577f8fd19ee0d2d407479cc70e521adc367f37
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsReader.java

 		for (;;) {
 			dstoff = block.inflate(inf, position, dstbuf, dstoff);
 
-			if (headerOnly & dstoff == dstbuf.length)
+			if (headerOnly && dstoff == dstbuf.length)
 				return dstoff;
 			if (inf.needsInput()) {
 				position += block.remaining(position);