Print assertion failure to log and flush even if DEBUG is not defined

TR_ASSERT_FATAL() could fail in any build, and in particular in builds
without DEBUG. Previously, if such a failure occurred with tracing
enabled, the process would crash without printing the failure to the
log, and more importantly, without flushing previously written trace
output, which was confusing and impeded debugging.

compiler/compile/OMRCompilation.cpp

@@ -2483,17 +2483,14 @@ TR_Debug * OMR::Compilation::findOrCreateDebug()
 
 void OMR::Compilation::diagnosticImpl(const char *s, ...)
    {
-#if defined(DEBUG)
    va_list ap;
    va_start(ap, s);
    self()->diagnosticImplVA(s, ap);
    va_end(ap);
-#endif
    }
 
 void OMR::Compilation::diagnosticImplVA(const char *s, va_list ap)
    {
-#if defined(DEBUG)
    if (self()->getOutFile() != NULL)
       {
       va_list copy;
@@ -2504,7 +2501,6 @@ void OMR::Compilation::diagnosticImplVA(const char *s, va_list ap)
       trfflush(self()->getOutFile());
       va_end(copy);
       }
-#endif
    }