This fixes a bug with the libevent backend on 32-bit platforms:

  https://github.com/wingo/fibers/issues/86

diff --git a/extensions/libevent.c b/extensions/libevent.c
index 4f44de9..52c9d73 100644
--- a/extensions/libevent.c
+++ b/extensions/libevent.c
@@ -215,7 +215,8 @@ run_event_loop (void *p)
     microsec = -1;
   else if (data->timeout >= 0)
     {
-      microsec = data->timeout / time_units_per_microsec;
+      microsec = (time_units_per_microsec == 0)
+	? 0 : data->timeout / time_units_per_microsec;
       tv.tv_sec = 0;
       tv.tv_usec = microsec;
     }
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<tr><td><span title='2020-01-08 21:56:04 +0100'>2020-01-08</span></td><td><a href='/guix/commit/gnu/packages/patches/doxygen-test.patch?id=b34c1258515e75bcc73be7911fd7d237db1dd14b'>gnu: doxygen: Update to 1.8.17.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/documentation.scm (doxygen): Update to 1.8.17.
[source](patches): Add doxygen-1.8.17-runtests.patch.
[arguments]: Remove obsolete phase.
* gnu/packages/patches/doxygen-test.patch: Adjust for upstream changes.
* gnu/packages/patches/doxygen-1.8.17-runtests.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-12-05 17:59:02 +0100'>2019-12-05</span></td><td><a href='/guix/commit/gnu/packages/patches/doxygen-test.patch?id=33c1c4c95fc8311606f1d513a06bc365607d4f6c'>gnu: doxygen: Update to 1.8.16.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/documentation.scm (doxygen): Update to 1.8.16.
[arguments]: Add phase 'remove-git-requirement'.
* gnu/packages/patches/doxygen-test.patch: Adjust for upstream changes.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-02-14 00:21:30 +0100'>2019-02-14</span></td><td><a href='/guix/commit/gnu/packages/patches/doxygen-test.patch?id=0add9c52637659eb5e09797f2c9e9be7bf7e9989'>gnu: doxygen: Update to 1.8.15.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/documentation.scm (doxygen): Update to 1.8.15.
* gnu/packages/patches/doxygen-test.patch: Update for upstream changes.
</span></span></td><td>Marius Bakke</td></tr>