MDEV-35394 Innochecksum misinterprets freed pages

- Innochecksum misinterprets the freed pages as active one.
This leads the user to think there are too many valid
pages exist.

- To avoid this confusion, innochecksum introduced one
more option --skip-freed-pages and -r to avoid the freed
pages while dumping or printing the summary of the tablespace.

- Innochecksum can safely assume the page is freed if
the respective extent doesn't belong to a segment and marked as
freed in XDES_BITMAP in extent descriptor page.

- Innochecksum shouldn't assume that zero-filled page as extent
descriptor page.

Reviewed-by: Marko Mäkelä

mysql-test/suite/innodb_zip/r/innochecksum_2.result

@@ -34,6 +34,7 @@ per-page-details                  FALSE
 log                               (No default value)
 leaf                              FALSE
 merge                             0
+skip-freed-pages                  FALSE
 [1]:# check the both short and long options for "help"
 [2]:# Run the innochecksum when file isn't provided.
 # It will print the innochecksum usage similar to --help option.
@@ -41,7 +42,7 @@ innochecksum Ver #.#.#
 Copyright (c) YEAR, YEAR , Oracle, MariaDB Corporation Ab and others.
 
 InnoDB offline file checksum utility.
-Usage: innochecksum [-c] [-s <start page>] [-e <end page>] [-p <page>] [-i] [-v]  [-a <allow mismatches>] [-n] [-S] [-D <page type dump>] [-l <log>] [-l] [-m <merge pages>] <filename or [-]>
+Usage: innochecksum [-c] [-r] [-s <start page>] [-e <end page>] [-p <page>] [-i] [-v]  [-a <allow mismatches>] [-n] [-S] [-D <page type dump>] [-l <log>] [-l] [-m <merge pages>] <filename or [-]>
 See https://mariadb.com/kb/en/library/innochecksum/ for usage hints.
   -?, --help          Displays this help and exits.
   -I, --info          Synonym for --help.
@@ -66,6 +67,8 @@ See https://mariadb.com/kb/en/library/innochecksum/ for usage hints.
   -f, --leaf          Examine leaf index pages
   -m, --merge=#       leaf page count if merge given number of consecutive
                       pages
+  -r, --skip-freed-pages 
+                      skip freed pages for the tablespace
 
 Variables (--variable-name=value)
 and boolean options {FALSE|TRUE}  Value (after reading options)
@@ -84,6 +87,7 @@ per-page-details                  FALSE
 log                               (No default value)
 leaf                              FALSE
 merge                             0
+skip-freed-pages                  FALSE
 [3]:# check the both short and long options for "count" and exit
 Number of pages:#
 Number of pages:#

mysql-test/suite/innodb_zip/r/innochecksum_3.result

@@ -139,6 +139,7 @@ per-page-details                  FALSE
 log                               (No default value)
 leaf                              FALSE
 merge                             0
+skip-freed-pages                  FALSE
 [5]: Page type dump for with shortform for tab1.ibd