MDEV-14425 fixup for MDEV-25312: Remove dead code

In commit cf552f5 we removed the
function os_normalize_path() and started writing file names to the
InnoDB redo log always using the same path separator, even on
Microsoft Windows.

In commit 685d958 the ability to
recover from previous log file formats was removed. Thus, the log file
can never contain the Microsoft specific path separator and the
conversion code can be removed.

Note: *.isl files may still contain Microsoft Windows path separators.
They will be replaced with standard ones in read_link_file().

storage/innobase/log/log0recv.cc

@@ -651,22 +651,12 @@ static struct
     {
       /* Replace absolute DATA DIRECTORY file paths with
       short names relative to the backup directory. */
-      const char *name= strrchr(filename, '/');
-#ifdef _WIN32
-      if (const char *last= strrchr(filename, '\\'))
-        if (last > name)
-          name= last;
-#endif
-      if (name)
+      if (const char *name= strrchr(filename, '/'))
       {
-        while (--name > filename &&
-#ifdef _WIN32
-               *name != '\\' &&
-#endif
-               *name != '/');
+        while (--name > filename && *name != '/');
         if (name > filename)
           filename= name + 1;
-       }
+      }
     }
 
     char *fil_path= fil_make_filepath(nullptr, {filename, strlen(filename)},
@@ -832,21 +822,9 @@ static struct
     const char *filename= name.c_str();
     if (srv_operation == SRV_OPERATION_RESTORE)
     {
-      const char* tbl_name = strrchr(filename, '/');
-#ifdef _WIN32
-      if (const char *last = strrchr(filename, '\\'))
+      if (const char *tbl_name= strrchr(filename, '/'))
       {
-        if (last > tbl_name)
-          tbl_name = last;
-      }
-#endif
-      if (tbl_name)
-      {
-        while (--tbl_name > filename &&
-#ifdef _WIN32
-               *tbl_name != '\\' &&
-#endif
-               *tbl_name != '/');
+        while (--tbl_name > filename && *tbl_name != '/');
         if (tbl_name > filename)
           filename= tbl_name + 1;
       }