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)))
r><td>
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<div class='path'>path: <a href='/guix/log/?id=fb9acf422034d4f4d88befb2820626f35a7f997e'>root</a>/<a href='/guix/log/gnu?id=fb9acf422034d4f4d88befb2820626f35a7f997e'>gnu</a>/<a href='/guix/log/gnu/tests.scm?id=fb9acf422034d4f4d88befb2820626f35a7f997e'>tests.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/tests.scm?id=fb9acf422034d4f4d88befb2820626f35a7f997e&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-04-21 16:16:38 +0200'>2023-04-21</span></td><td><a href='/guix/commit/gnu/tests.scm?id=a09c7da8f8d8e732f969cf0a09aaa78f87032ab1'>tests: Fork and exec a new Guile for the marionette REPL.</a><span class='msg-avail'>...<span class='msg-tooltip'>By merely forking PID 1, details from PID 1 (shepherd) would leak into
the marionette process, such as the set of modules in scope and state
inherited from the shepherd process (&lt;service&gt; instances, fibers,
etc.).  Running a fresh Guile instance avoids that.

* gnu/tests.scm (marionette-program): New procedure.
(marionette-shepherd-service): Change 'start' to use
'make-forkexec-constructor', and run the result of 'marionette-program'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-05-18 22:29:54 +0200'>2022-05-18</span></td><td><a href='/guix/commit/gnu/tests.scm?id=9a5d68692314bebd16dbcdc0d4e4e52fa4d5812f'>services: Add more description fields.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services.scm (simple-service): Add 'description' field.
* gnu/services/base.scm (udev-rules-service): Likewise.
* gnu/system/install.scm (configuration-template-service-type): Likewise.
* gnu/tests.scm (marionette-service-type): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>