DEBUG flags cleanup, some dead code removal

signal.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <signal.h>
+
+int sigint_received=0;
+
+static void stopall()
+{
+    printf("SIGINT RECEIVED: aborting eval\n");
+    sigint_received=1;
+}
+
+int stopped()
+{
+    return sigint_received;
+}
+
+void set_intr()
+{
+    signal(SIGINT, stopall);
+#   ifdef DEBUG
+    printf("SIGINT armed.\n");
+#   endif
+}