Test programmers for prog_modes and type

This corrects the error message when AVRDUDE cannot use a programmer to
say it is owing to lack of prog_modes or type.

src/main.c

@@ -442,11 +442,15 @@ static int dev_opt(const char *str) {
 }
 
 
-static void programmer_not_found(const char *programmer) {
+static void programmer_not_found(const char *programmer, PROGRAMMER *pgm) {
   msg_error("\n");
-  if(programmer && *programmer)
-    pmsg_error("cannot find programmer id %s\n", programmer);
-  else {
+  if(programmer && *programmer) {
+    if(!pgm || !pgm->id || !lsize(pgm->id))
+      pmsg_error("cannot find programmer id %s\n", programmer);
+    else
+      pmsg_error("programmer %s lacks %s setting\n", programmer,
+        !pgm->prog_modes? "prog_modes": !pgm->initpgm? "type": "some");
+  } else {
     pmsg_error("no programmer has been specified on the command line or in the\n");
     imsg_error("config file(s); specify one using the -c option and try again\n");
   }
@@ -1057,7 +1061,7 @@ int main(int argc, char * argv [])
       if(pgmid && *pgmid && explicit_c) {
         PROGRAMMER *pgm = locate_programmer_set(programmers, pgmid, &pgmid);
         if(!pgm || !is_programmer(pgm)) {
-          programmer_not_found(pgmid);
+          programmer_not_found(pgmid, pgm);
           exit(1);
         }
         msg_error("\nValid parts for programmer %s are:\n", pgmid);
@@ -1100,13 +1104,13 @@ int main(int argc, char * argv [])
   msg_notice("\n");
 
   if(!pgmid || !*pgmid) {
-    programmer_not_found(NULL);
+    programmer_not_found(NULL, NULL);
     exit(1);
   }
 
   pgm = locate_programmer_set(programmers, pgmid, &pgmid);
   if (pgm == NULL || !is_programmer(pgm)) {
-    programmer_not_found(pgmid);
+    programmer_not_found(pgmid, pgm);
     exit(1);
   }