Do not introduce timestamps in PNG files (for icons).
See <https://wiki.debian.org/ReproducibleBuilds/TimestampsInPNG>.

--- awesome-3.4.15/CMakeLists.txt	2013-02-11 14:50:21.000000000 +0100
+++ awesome-3.4.15/CMakeLists.txt	2016-06-16 13:59:30.528125439 +0200
@@ -295,7 +295,7 @@ macro(a_icon_convert match replacement i
         set(ALL_ICONS ${ALL_ICONS} ${output})
 
         add_custom_command(
-            COMMAND ${CONVERT_EXECUTABLE} ${input} -strip ${ARGN} ${output}
+            COMMAND ${CONVERT_EXECUTABLE} +set date:create +set date:modify -define png:exclude-chunk=time ${input} -strip ${ARGN} ${output}
             OUTPUT  ${output}
             DEPENDS ${input}
             VERBATIM)
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<tr><td><span title='2023-07-16 02:00:01 +0200'>2023-07-16</span></td><td><a href='/guix/commit/gnu/packages/diffoscope.scm?id=dbaa8fdfaf131642e6ba083e1c5bc53ac72fe4f7'>gnu: diffoscope: Update to 245.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2023-07-16 02:00:11 +0200'>2023-07-16</span></td><td><a href='/guix/commit/gnu/packages/diffoscope.scm?id=ba9fdaa81439004889f944f6ccef794abd33c907'>gnu: diffoscope: Don't embed build-time references.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2023-07-16 02:00:10 +0200'>2023-07-16</span></td><td><a href='/guix/commit/gnu/packages/diffoscope.scm?id=aeb6cdacbc3e245c515cd2c1dde869c462754687'>gnu: diffoscope: Use G-expressions.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2023-07-16 02:00:10 +0200'>2023-07-16</span></td><td><a href='/guix/commit/gnu/packages/diffoscope.scm?id=2db3fa4a7677ee7b7491bf037cf5e12ab1206ef3'>gnu: diffoscope: Update to 244.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2023-05-13 18:38:28 +0800'>2023-05-13</span></td><td><a href='/guix/commit/gnu/packages/diffoscope.scm?id=882ca2011e28d8246b41775b9439cb4fa44aa2d4'>gnu: diffoscope: Update to 242.</a><span class='msg-avail'>...</span></td><td>Vagrant Cascadian</td></tr>
<tr><td><span title='2023-04-14 17:15:08 -0400'>2023-04-14</span></td><td><a href='/guix/commit/gnu/packages/diffoscope.scm?id=3bacd3c76a58ebe70f98be654f09cbd4166093ab'>Merge branch 'master' into core-updates.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>