Don't apply E8 transform on 32769th frame (off-by-one error)

Author: kyz

libmspack/ChangeLog

@@ -1,3 +1,12 @@
+2020-01-08  Stuart Caie <kyzer@cabextract.org.uk>
+
+	* lzxd_decompress(): do not apply the E8 transformation on the
+	32769th LZX frame! Thanks to Cezary Sliwa for discovering this
+	bug and providing an example cab file (which is
+	http://download.windowsupdate.com/d/msdownload/update/driver/
+	drvs/2019/11/016c7f3e-809d-4720-893b-
+	e0d74f10c39d_35e12507628e8dc8ae5fb3332835f4253d2dab23.cab)
+
 2019-02-18  Stuart Caie <kyzer@cabextract.org.uk>
 
 	* chmd_read_headers(): a CHM file name beginning "::" but shorter

libmspack/mspack/lzxd.c

@@ -827,7 +827,7 @@ int lzxd_decompress(struct lzxd_stream *lzx, off_t out_bytes) {
 
     /* does this intel block _really_ need decoding? */
     if (lzx->intel_started && lzx->intel_filesize &&
-        (lzx->frame <= 32768) && (frame_size > 10))
+        (lzx->frame < 32768) && (frame_size > 10))
     {
       unsigned char *data    = &lzx->e8_buf[0];
       unsigned char *dataend = &lzx->e8_buf[frame_size - 10];