sim: info: convert verbose field to a bool

The verbose argument has always been an int treated as a bool, so
convert it to an explicit bool.  Further, update the API docs to
match the reality that the verbose value is actually used by some
of the internal modules.

sim/m32c/gdb-if.c

@@ -705,7 +705,7 @@ sim_memory_map (SIM_DESC sd)
 }
 
 void
-sim_info (SIM_DESC sd, int verbose)
+sim_info (SIM_DESC sd, bool verbose)
 {
   printf ("The m32c minisim doesn't collect any statistics.\n");
 }