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)))
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<div class='path'>path: <a href='/guix/log/?id=deda3cc9057f20b1e3d34d63a64da0bdd6ca1998'>root</a>/<a href='/guix/log/guix.scm?id=deda3cc9057f20b1e3d34d63a64da0bdd6ca1998'>guix.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/guix.scm?id=deda3cc9057f20b1e3d34d63a64da0bdd6ca1998&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-07-12 01:17:45 +0200'>2022-07-12</span></td><td><a href='/guix/commit/guix.scm?id=4574ef267e543bcac97d9c400f30cb731df29181'>guix: Really export 'define-public'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-09-14 11:50:58 +0200'>2021-09-14</span></td><td><a href='/guix/commit/guix.scm?id=3858275962f1ac567b5dce2355035f9eddea0a05'>guix: Replace 'define-public'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-06-29 00:00:13 +0200'>2021-06-29</span></td><td><a href='/guix/commit/guix.scm?id=e059adcb6001ab0353d969b24030d0c342f8830e'>(guix) no longer pulls in (guix ftp-client).</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
tr>
<tr><td><span title='2022-12-23 20:20:06 +0100'>2022-12-23</span></td><td><a href='/guix/commit/etc/guix-daemon.cil.in?id=4a134ed32e69ba888d988d2ed924a1531a54551b'>etc: SELinux: Allow daemon to search run state directories.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2022-12-23 20:20:06 +0100'>2022-12-23</span></td><td><a href='/guix/commit/etc/guix-daemon.cil.in?id=f28d792719abb82cc920486e6d6f14eacc44370c'>etc: SELinux: Label guix-daemon executable in profile.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2022-01-26 09:31:45 +0100'>2022-01-26</span></td><td><a href='/guix/commit/etc/guix-daemon.cil.in?id=bbc2fb0d52128c85c92251ed36d8063b3dcf3c3a'>etc: Remove redundant SELinux permissions block.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-01-24 11:28:14 +0100'>2022-01-24</span></td><td><a href='/guix/commit/etc/guix-daemon.cil.in?id=98e74d520a30d1ed7d7b47d4f1d9afadefc699e3'>etc: Add more SELinux permissions for the daemon.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>