branches/zip: page_zip_compress(): Flag the compressed stream completely

initialized, although Valgrind believes that some bits in the 7th or 8th
bytes from the end are uninitialized.  (They might be, but the decompressor
should not care about those bits after encountering the end-of-stream marker
in the compressed bit stream.)

page/page0zip.c

@@ -1221,6 +1221,10 @@ page_zip_compress(
 	ut_ad(buf + c_stream.total_out == c_stream.next_out);
 	ut_ad((ulint) (storage - c_stream.next_out) >= c_stream.avail_out);
 
+	/* Valgrind believes that zlib does not initialize some bits
+	in the last 7 or 8 bytes of the stream.  Make Valgrind happy. */
+	UNIV_MEM_VALID(buf, c_stream.total_out);
+
 	/* Zero out the area reserved for the modification log.
 	Space for the end marker of the modification log is not
 	included in avail_out. */