MDEV-16045: Fix a heap allocation

Since commit baa5a43
changed the allocation of log_t::files::file_header_bufs[],
a memory overrun could occur when running with a non-default
setting of innodb_log_files_in_group.

log_t::files::create(): Correctly allocate n_files*2048 + 512
bytes of memory, to be aligned at a 512-byte boundary.

storage/innobase/log/log0log.cc

@@ -675,9 +675,8 @@ void log_t::files::create(ulint n_files)
   lsn= LOG_START_LSN;
   lsn_offset= LOG_FILE_HDR_SIZE;
 
-  byte* ptr= static_cast<byte*>(ut_zalloc_nokey(LOG_FILE_HDR_SIZE
-						+ OS_FILE_LOG_BLOCK_SIZE
-						* n_files));
+  byte* ptr= static_cast<byte*>(ut_zalloc_nokey(LOG_FILE_HDR_SIZE * n_files
+						+ OS_FILE_LOG_BLOCK_SIZE));
   file_header_bufs_ptr= ptr;
   ptr= static_cast<byte*>(ut_align(ptr, OS_FILE_LOG_BLOCK_SIZE));