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=c0fe2e1f03694cf7b29d418119c3ed0223973d59'>refs</a><a class='active' href='/guix/log/gnu/packages/hugs.scm'>log</a><a href='/guix/tree/gnu/packages/hugs.scm?id=c0fe2e1f03694cf7b29d418119c3ed0223973d59'>tree</a><a href='/guix/commit/gnu/packages/hugs.scm?id=c0fe2e1f03694cf7b29d418119c3ed0223973d59'>commit</a><a href='/guix/diff/gnu/packages/hugs.scm?id=c0fe2e1f03694cf7b29d418119c3ed0223973d59'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/hugs.scm'>
<input type='hidden' name='id' value='c0fe2e1f03694cf7b29d418119c3ed0223973d59'/><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=c0fe2e1f03694cf7b29d418119c3ed0223973d59'>root</a>/<a href='/guix/log/gnu?id=c0fe2e1f03694cf7b29d418119c3ed0223973d59'>gnu</a>/<a href='/guix/log/gnu/packages?id=c0fe2e1f03694cf7b29d418119c3ed0223973d59'>packages</a>/<a href='/guix/log/gnu/packages/hugs.scm?id=c0fe2e1f03694cf7b29d418119c3ed0223973d59'>hugs.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/hugs.scm?id=c0fe2e1f03694cf7b29d418119c3ed0223973d59&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>