add new function for debug in Lama: LprintfPerrror --- synonym for fprintf(perror,...)

runtime/Std.i

@@ -23,6 +23,7 @@ F,regexpMatch;
 F,sprintf;
 F,makeString;
 F,printf;
+F,printfPerror;
 F,fprintf;
 F,fopen;
 F,fclose;

runtime/runtime.c

@@ -987,6 +987,19 @@ extern void Lfailure (char *s, ...) {
   vfailure(s, args);
 }
 
+extern void LprintfPerror (char *s, ...) {
+  va_list args = (va_list)BOX(NULL);
+
+  ASSERT_STRING("printfPerror:1", s);
+
+  va_start(args, s);
+  fix_unboxed(s, args);
+
+  if (vfprintf(stderr, s, args) < 0) { failure("printfPerror (...): %s\n", strerror(errno)); }
+
+  fflush(stderr);
+}
+
 extern void Bmatch_failure (void *v, char *fname, int line, int col) {
   createStringBuf();
   printValue(v);