numparam/spicenum.c, bug #300, exit gracefully upon numparam error (SHARED_MODULE)

Thanks to Sergii Baitala, who reported this in
  #300 Shared ngspice: ngspice hangs on getchar
  http://sourceforge.net/p/ngspice/bugs/300/

src/frontend/numparam/spicenum.c

@@ -28,6 +28,9 @@ Todo:
 
 #include "ngspice/fteext.h"
 
+#ifdef SHARED_MODULE
+extern void shared_exit(int status);
+#endif
 
 extern bool ft_batchmode;
 
@@ -494,6 +497,12 @@ nupa_done(void)
        simulation has finished. */
 
     if (nerrors) {
+
+#ifdef SHARED_MODULE
+        fprintf(cp_err, "Numparam expansion errors: Problem with input file.\n");
+        shared_exit(EXIT_BAD);
+#endif
+
         printf(" Copies=%d Evals=%d Placeholders=%ld Symbols=%d Errors=%d\n",
                linecountS, evalcountS, placeholder, dictsize, nerrors);
         /* debug: ask if spice run really wanted */