comics: Fix use-after-free

Fix use-after-free when attempting to access files after the archive has been reset. We would try to avoid reopening the archive but it was already closed and the entry was pointing to invalid memory.

==12603== Invalid read of size 8
==12603==    at 0x154303FF: archive_entry_pathname (archive_entry.c:575)
==12603==    by 0x15411059: archive_reopen_if_needed.constprop.0 (comics-document.c:156)
==12603==    by 0x1541111F: comics_document_get_page_size (comics-document.c:444)
==12603==    by 0x486EAE1: _ev_document_get_page_size (ev-document.c:860)
==12603==    by 0x486EAE1: ev_document_get_page_size (ev-document.c:897)
==12603==    by 0x4029C3: evince_thumbnail_pngenc_get (evince-thumbnailer.c:207)
==12603==    by 0x4024F1: main (evince-thumbnailer.c:329)
==12603==  Address 0x6aa08b0 is 0 bytes inside a block of size 1,280 free'd
==12603==    at 0x48480E4: free (vg_replace_malloc.c:872)
==12603==    by 0x1543E6DA: _archive_read_free (archive_read.c:1123)
==12603==    by 0x1543E6DA: _archive_read_free (archive_read.c:1070)
==12603==    by 0x15412056: ev_archive_reset (ev-archive.c:311)
==12603==    by 0x15410C1B: comics_document_list (comics-document.c:272)
==12603==    by 0x15410C1B: comics_document_load (comics-document.c:379)
==12603==    by 0x486DF51: ev_document_load_full (ev-document.c:415)
==12603==    by 0x48702C5: ev_document_factory_get_document_full (ev-document-factory.c:320)
==12603==    by 0x40247C: evince_thumbnailer_get_document (evince-thumbnailer.c:170)
==12603==    by 0x40247C: main (evince-thumbnailer.c:297)
==12603==  Block was alloc'd at
==12603==    at 0x484A464: calloc (vg_replace_malloc.c:1328)
==12603==    by 0x1542FD1A: archive_entry_new2 (archive_entry.c:269)
==12603==    by 0x1543DB26: archive_read_new (archive_read.c:102)
==12603==    by 0x15411743: libarchive_set_archive_type (ev-archive.c:78)
==12603==    by 0x1541195E: ev_archive_set_archive_type (ev-archive.c:113)
==12603==    by 0x15410D4E: comics_check_decompress_support (comics-document.c:301)
==12603==    by 0x15410D4E: comics_document_load (comics-document.c:372)
==12603==    by 0x486DF51: ev_document_load_full (ev-document.c:415)
==12603==    by 0x48702C5: ev_document_factory_get_document_full (ev-document-factory.c:320)
==12603==    by 0x40247C: evince_thumbnailer_get_document (evince-thumbnailer.c:170)
==12603==    by 0x40247C: main (evince-thumbnailer.c:297)

Fixes: b1732c19 Closes: #1776 (closed)

(cherry picked from commit b4bdbc42)