Wrong initial value for srv_track_changed_pages

[Alexey Kopytov]

srv_track_changed_pages is defined in srv0srv.c[c] as follows:

UNIV_INTERN my_bool srv_track_changed_pages = TRUE;

Which contradicts the corresponding server option's default value (FALSE). Since option parsing is performed before the changed pages tracking is initialized, it is changed from its initial value to FALSE on startup, so everything accidentally works as documented.

It only becomes a problem when XtraBackup is rebased on the newer PS versions. Since XtraBackup doesn't use the plugin options parsing facility (and thus ignores innodb_track_changed_pages and its default value), it uses the initial value defined srv0srv. As a result, XtraBackup recovery starts with page tracking enabled.