[flang] Rename the runtime routine that reports a fatal user error

[PeteSteinfeld]

Summary

As per Steve Scalpone's suggestion, I've renamed the runtime routine to
better evoke its purpose.

I implemented a routine called "Crash" and added a test.

flang/include/flang/Runtime/stop.h

 NORETURN void RTNAME(ProgramEndStatement)(NO_ARGUMENTS);
 
 // Extensions
 NORETURN void RTNAME(Exit)(int status = EXIT_SUCCESS);
 NORETURN void RTNAME(Abort)(NO_ARGUMENTS);
 
 // Crash with an error message when the program dynamically violates a Fortran
 // constraint.
-NORETURN void RTNAME(Crash)(const char *message, const char *source, int line);
+NORETURN void RTNAME(ReportFatalUserError)(
+    const char *message, const char *source, int line);
 
 FORTRAN_EXTERN_C_END
 
 #endif // FORTRAN_RUNTIME_STOP_H_

flang/runtime/stop.cpp

 
 [[noreturn]] void RTNAME(Exit)(int status) {
   CloseAllExternalUnits("CALL EXIT()");
   std::exit(status);
 }
 
 [[noreturn]] void RTNAME(Abort)() { std::abort(); }
 
-[[noreturn]] void RTNAME(Crash)(
+[[noreturn]] void RTNAME(ReportFatalUserError)(
     const char *message, const char *source, int line) {
   Fortran::runtime::Terminator{source, line}.Crash(message);
 }
 }

flang/unittests/Runtime/Stop.cpp

 
 TEST(TestProgramEnd, CrashTest) {
   static const std::string crashMessage{"bad user code"};
   static const std::string fileName{"file name"};
   static const std::string headMessage{"fatal Fortran runtime error\\("};
   static const std::string tailMessage{":343\\): "};
   static const std::string fullMessage{
       headMessage + fileName + tailMessage + crashMessage};
-  EXPECT_DEATH(RTNAME(Crash)(crashMessage.c_str(), fileName.c_str(), 343),
+  EXPECT_DEATH(
+      RTNAME(ReportFatalUserError)(crashMessage.c_str(), fileName.c_str(), 343),
       fullMessage.c_str());
 }