Use Qt for error reports

Utilities/Thread.h

@@ -10,6 +10,9 @@
 #include "sema.h"
 #include "cond.h"
 
+// Report error and call std::abort(), defined in main.cpp
+[[noreturn]] void report_fatal_error(const std::string&);
+
 // Will report exception and call std::abort() if put in catch(...)
 [[noreturn]] void catch_all_exceptions();