Fix compatibility with newer Boost.

Extracted from this upstream commit:
https://cgit.freedesktop.org/libreoffice/core/commit/?id=23a8d5ffbbe58761b89f590f0735abccd69a3681

diff --git a/sfx2/source/appl/shutdownicon.cxx b/sfx2/source/appl/shutdownicon.cxx
--- a/sfx2/source/appl/shutdownicon.cxx
+++ b/sfx2/source/appl/shutdownicon.cxx
@@ -144,7 +144,7 @@ bool LoadModule()
 #endif // ENABLE_QUICKSTART_APPLET
     }
     assert(!boost::logic::indeterminate(loaded));
-    return loaded;
+    return bool(loaded);
 }
 
 }
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<tr><td><span title='2020-07-25 19:11:37 +0200'>2020-07-25</span></td><td><a href='/guix/commit/gnu.scm?id=d51bfe242fbe6f3f8f71d723e8fe0c7bbe711ba1'>Use 'formatted-message' instead of '&amp;message' where appropriate.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-07-25 19:11:36 +0200'>2020-07-25</span></td><td><a href='/guix/commit/gnu.scm?id=f9a8dd053c4e0fd1fc4b64291bb90de36520b3bc'>utils: Move '&amp;fix-hint' to (guix diagnostics).</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
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