This patch adds an include needed since icu59:
Source: https://git.archlinux.org/svntogit/community.git/plain/trunk/icu59.patch?h=packages/aegisub
--- aegisub-3.2.2/src/utils.cpp	2014-12-08 02:07:09.000000000 +0200
+++ aegisub-3.2.2/src/utils.cpp	2017-04-26 11:11:15.438239182 +0300
@@ -44,6 +44,7 @@
 #include <boost/filesystem/path.hpp>
 #include <map>
 #include <unicode/locid.h>
+#include <unicode/unistr.h>
 #include <wx/clipbrd.h>
 #include <wx/filedlg.h>
 #include <wx/stdpaths.h>
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<tr><td><span title='2022-05-12 19:27:59 +0200'>2022-05-12</span></td><td><a href='/guix/commit/doc/images?id=eeba993f570483345acd59c2d8709fd5d7ee7ae7'>doc: Add the "Full-source Bootstrap".</a><span class='msg-avail'>...</span></td><td>Jan (janneke) Nieuwenhuizen</td></tr>
<tr><td><span title='2020-05-22 16:11:52 +0200'>2020-05-22</span></td><td><a href='/guix/commit/doc/images?id=cd5d5f53228fd5bf96d9f790aa2606ae71fa68d7'>doc: Update 'Bootstrapping' for further binary seed reduction.</a><span class='msg-avail'>...</span></td><td>Jan Nieuwenhuizen</td></tr>