tcc -run file.c : pass original exit code from file.c again

when there are no other errors then exit tcc with the exit cude
from tcc_run() (messed up in dd2e5f8)

Also in tccrun.c, use a more exotic random value to replace zero
with 'exit(0)' in user code (because lonhjmp(jb, c) needs c != 0)

tcc.c

@@ -378,8 +378,9 @@ int main(int argc0, char **argv0)
                 first_file = f->name;
             ret = tcc_add_file(s, f->name);
         }
-        done = ret || ++n >= s->nb_files;
-    } while (!done && (s->output_type != TCC_OUTPUT_OBJ || s->option_r));
+    } while (++n < s->nb_files
+            && 0 == ret
+            && (s->output_type != TCC_OUTPUT_OBJ || s->option_r));
 
     if (s->do_bench)
         end_time = getclock_ms();
@@ -406,13 +407,17 @@ int main(int argc0, char **argv0)
     done = 1;
     if (t)
         done = 0; /* run more tests with -dt -run */
-    else if (ret)
-        ret = 1;
-    else if (n < s->nb_files)
+    else if (ret) {
+        if (s->nb_errors)
+            ret = 1;
+        /* else keep the original exit code from tcc_run() */
+    } else if (n < s->nb_files)
         done = 0; /* compile more files with -c */
     else if (s->do_bench)
         tcc_print_stats(s, end_time - start_time);
+
     tcc_delete(s);
+
     if (!done)
         goto redo;
     if (ppfp && ppfp != stdout)

tccrun.c

@@ -197,6 +197,8 @@ ST_FUNC void tcc_run_free(TCCState *s1)
 #endif
 }
 
+#define RT_EXIT_ZERO 0xE0E00E0E /* passed from longjmp instead of '0' */
+
 /* launch the compiled program with the given arguments */
 LIBTCCAPI int tcc_run(TCCState *s1, int argc, char **argv)
 {
@@ -238,7 +240,7 @@ LIBTCCAPI int tcc_run(TCCState *s1, int argc, char **argv)
     ret = tcc_setjmp(s1, main_jb, tcc_get_symbol(s1, top_sym));
     if (0 == ret)
         ret = prog_main(argc, argv, envp);
-    else if (256 == ret)
+    else if (RT_EXIT_ZERO == ret)
         ret = 0;
 
     if (s1->dflag & 16 && ret) /* tcc -dt -run ... */
@@ -596,7 +598,7 @@ static void rt_exit(rt_frame *f, int code)
     rt_post_sem();
     if (s && s->run_lj) {
         if (code == 0)
-            code = 256;
+            code = RT_EXIT_ZERO;
         ((void(*)(void*,int))s->run_lj)(s->run_jb, code);
     }
     exit(code);