Fix doc snarfing with GCC 4.5+.
From <http://git.savannah.gnu.org/cgit/guile.git/commit/?h=branch_release-1-8&id=aac41d28358cea594bb30f6e547afb82bb6004a6>.

diff --git a/scripts/snarf-check-and-output-texi b/scripts/snarf-check-and-output-texi
index ea33e17..8cd42e8 100755
--- a/scripts/snarf-check-and-output-texi
+++ b/scripts/snarf-check-and-output-texi
@@ -267,6 +267,17 @@ exec ${GUILE-guile} -l $0 -c "(apply $main (cdr (command-line)))" "$@"
       (set! *file* file)
       (set! *line* line))
 
+     ;; newer gccs like to throw around more location markers into the
+     ;; preprocessed source; these (hash . hash) bits are what they translate to
+     ;; in snarfy terms.
+     (('location ('string . file) ('int . line) ('hash . 'hash))
+      (set! *file* file)
+      (set! *line* line))
+
+     (('location ('hash . 'hash) ('string . file) ('int . line) ('hash . 'hash))
+      (set! *file* file)
+      (set! *line* line))
+
      (('arglist rest ...)
       (set! *args* (do-arglist rest)))
 class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a'>refs</a><a class='active' href='/guix/log/gnu/packages/ibus.scm'>log</a><a href='/guix/tree/gnu/packages/ibus.scm?id=8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a'>tree</a><a href='/guix/commit/gnu/packages/ibus.scm?id=8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a'>commit</a><a href='/guix/diff/gnu/packages/ibus.scm?id=8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/ibus.scm'>
<input type='hidden' name='id' value='8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a'>root</a>/<a href='/guix/log/gnu?id=8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a'>gnu</a>/<a href='/guix/log/gnu/packages?id=8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a'>packages</a>/<a href='/guix/log/gnu/packages/ibus.scm?id=8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a'>ibus.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/ibus.scm?id=8c9bc0e710bbb503d9dc6a9c135876b4d8bdbc2a&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-09-05 19:50:43 -0400'>2023-09-05</span></td><td><a href='/guix/commit/gnu/packages/ibus.scm?id=3d351a631bcbf3fc3d072cb9395ef4b1ceb16b3d'>gnu: ibus: Add search-path for 'GUIX_GTK3_IM_MODULE_FILE'.</a><span class='msg-avail'>...</span></td><td>宋文武</td></tr>
<tr><td><span title='2023-09-05 19:50:42 -0400'>2023-09-05</span></td><td><a href='/guix/commit/gnu/packages/ibus.scm?id=9809f27657a6a16a4bbb45d8b571a6f92e6e2117'>gnu: ibus: Disable registry cache.</a><span class='msg-avail'>...</span></td><td>宋文武</td></tr>
<tr><td><span title='2023-08-22 12:34:20 -0400'>2023-08-22</span></td><td><a href='/guix/commit/gnu/packages/ibus.scm?id=13425768f7c393cda49302ba2e8705f14ae56f0d'>gnu: ibus-anthy: Update to 1.5.15.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2023-08-03 18:30:45 +0800'>2023-08-03</span></td><td><a href='/guix/commit/gnu/packages/ibus.scm?id=782cf09b84bc72514e89d783460ea98bc353bf6a'>gnu: Add ibus-table-others.</a><span class='msg-avail'>...</span></td><td>Nguyễn Gia Phong</td></tr>
<tr><td><span title='2023-08-03 18:30:45 +0800'>2023-08-03</span></td><td><a href='/guix/commit/gnu/packages/ibus.scm?id=4eeb35595b05d7a3c83de1f901b3edffcafe9df5'>gnu: Add ibus-table.</a><span class='msg-avail'>...</span></td><td>Nguyễn Gia Phong</td></tr>
<tr><td><span title='2023-08-03 18:30:45 +0800'>2023-08-03</span></td><td><a href='/guix/commit/gnu/packages/ibus.scm?id=55593beaba8328c16e3b1fa81197f4173fc17691'>gnu: ibus: Wrap ibus-daemon with GUIX_PYTHONPATH and GI_TYPELIB_PATH.</a><span class='msg-avail'>...</span></td><td>宋文武</td></tr>
<tr><td><span title='2023-07-30 13:42:38 +0800'>2023-07-30</span></td><td><a href='/guix/commit/gnu/packages/ibus.scm?id=9e245b50f87588212ae179eaf9cd41c05e06de4c'>gnu: ibus-anthy: Fix runtime errors.</a><span class='msg-avail'>...</span></td><td>宋文武</td></tr>