MDEV-28181 The innochecksum -w option was inadvertently removed

In commit 7a4fbb55b0 (MDEV-25105)
the innochecksum option --write (-w) was removed altogether.
It should have been made a Boolean option, so that old data files
may be converted to a format that is compatible with
innodb_checksum_algorithm=strict_crc32 by executing the following:

innochecksum -n -w ibdata* */*.ibd

It would be better to use an older-version innochecksum
for such a conversion, so that page checksums will be validated
before updating the checksum.

It never was possible for innochecksum to convert files to the
innodb_checksum_algorithm=full_crc32 format that is the default
for new InnoDB data files.

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

@@ -14,7 +14,8 @@ FOUND 1 /Error: --no-check must be associated with --write option./ in my_restar
 FOUND 1 /unknown variable 'strict-check=innodb'/ in my_restart.err
 [7]: check the innochecksum with short form strict-check & no-check , an error is expected
 FOUND 1 /unknown option '-C'/ in my_restart.err
-FOUND 1 /unknown variable 'write=crc32'/ in my_restart.err
+FOUND 1 /ignoring option '--write' due to invalid value 'crc32'/ in my_restart.err
+FOUND 1 /Error: --no-check must be associated with --write option/ in my_restart.err
 # restart
 SELECT * FROM tab1;
 c1	c2

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

@@ -27,6 +27,7 @@ end-page                          0
 page                              0
 no-check                          FALSE
 allow-mismatches                  0
+write                             FALSE
 page-type-summary                 FALSE
 page-type-dump                    MYSQLTEST_VARDIR/tmp/dump.txt
 per-page-details                  FALSE
@@ -54,6 +55,7 @@ See https://mariadb.com/kb/en/library/innochecksum/ for usage hints.
   -n, --no-check      Ignore the checksum verification.
   -a, --allow-mismatches=# 
                       Maximum checksum mismatch allowed.
+  -w, --write         Rewrite the checksum.
   -S, --page-type-summary 
                       Display a count of each page type in a tablespace.
   -D, --page-type-dump=name 
@@ -75,6 +77,7 @@ end-page                          0
 page                              0
 no-check                          FALSE
 allow-mismatches                  0
+write                             FALSE
 page-type-summary                 FALSE
 page-type-dump                    (No default value)
 per-page-details                  FALSE

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

@@ -133,6 +133,7 @@ end-page                          0
 page                              0
 no-check                          FALSE
 allow-mismatches                  0
+write                             FALSE
 page-type-summary                 FALSE
 page-type-dump                    MYSQLTEST_VARDIR/tmp/dump.txt
 per-page-details                  FALSE