Link boost_chrono on all platforms, not just Windows

smessage.cpp uses boost::chrono::steady_clock which requires
-lboost_chrono. Previously only linked on Windows.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

triangles-qt.pro

@@ -526,7 +526,7 @@ LIBS += -levent -lz
 windows:LIBS += -lws2_32 -lshlwapi -lmswsock -lole32 -loleaut32 -luuid -lgdi32 -lcrypt32
 
 LIBS += -lboost_filesystem$$BOOST_LIB_SUFFIX -lboost_program_options$$BOOST_LIB_SUFFIX -lboost_thread$$BOOST_THREAD_LIB_SUFFIX
-windows:LIBS += -lboost_chrono$$BOOST_LIB_SUFFIX
+LIBS += -lboost_chrono$$BOOST_LIB_SUFFIX
 
 contains(RELEASE, 1) {
     !windows:!macx {