src/view.c: valgrind: hackish fix of uninitialised value usage

src/view.c: valgrind: hackish fix of uninitialised value usage

valgrind log when run viewer
==9981== Conditional jump or move depends on uninitialised value(s)
==9981==    at 0x45891B: view_map_offset_and_column (view.c:584)
==9981==    by 0x458D5B: view_column_to_offset (view.c:917)
==9981==    by 0x458DD8: view_set_first_showed (view.c:1443)
==9981==    by 0x45B79F: view_new (view.c:4136)
==9981==    by 0x45B911: mc_internal_viewer (view.c:3969)
==9981==    by 0x423D85: view_file_at_line (cmd.c:132)
==9981==    by 0x423E78: do_view_cmd (cmd.c:217)
==9981==    by 0x45CDE7: buttonbar_call (widget.c:2425)
==9981==    by 0x45D754: buttonbar_callback (widget.c:2456)
==9981==    by 0x427D42: dlg_process_event (dialog.c:618)
==9981==    by 0x428035: run_dlg (dialog.c:789)
==9981==    by 0x43E708: main (main.c:1688)
==9981==  Uninitialised value was created by a stack allocation
==9981==    at 0x4586F0: view_map_offset_and_column (view.c:593)

Signed-off-by: Sergei Trofimovich <slyfox@inbox.ru>