[bitmap] Fix bitmaps on 64-bit

Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/bitmap.c

 
 	if ( bit >= bitmap->length )
 		return 0;
-	return ( bitmap->blocks[index] & mask );
+	return ( ( bitmap->blocks[index] & mask ) != 0 );
 }
 
 /**

src/include/ipxe/bitmap.h

  * @v bit		Bit index
  * @ret mask		Block mask
  */
-#define BITMAP_MASK( bit ) ( 1 << ( (bit) % BITMAP_BLKSIZE ) )
+#define BITMAP_MASK( bit ) ( 1UL << ( (bit) % BITMAP_BLKSIZE ) )
 
 /** A bitmap */
 struct bitmap {