PT-1997 Added error logs

bin/pt-query-digest

@@ -13281,6 +13281,9 @@ sub main {
          DSNParser    => $dp,
          opts         => { AutoCommit => 1 },
       );
+      if ($EVAL_ERROR) {
+          die ("Cannot connect to the explain database: $EVAL_ERROR")
+      }
       $ep_dbh->{InactiveDestroy}  = 1;  # Don't die on fork().
    }
 
@@ -13303,6 +13306,10 @@ sub main {
          DSNParser    => $dp,
          opts         => { AutoCommit => 1 },
       );
+      if ($EVAL_ERROR) {
+          die ("Cannot connect to the review database: $EVAL_ERROR")
+      }
+
       $qv_dbh->{InactiveDestroy}  = 1;  # Don't die on fork().
 
       my @db_tbl = @{$review_dsn}{qw(D t)};
@@ -13347,6 +13354,9 @@ sub main {
          DSNParser    => $dp,
          opts         => { AutoCommit => 1 },
       );
+      if ($EVAL_ERROR) {
+          die ("Cannot connect to the history database: $EVAL_ERROR")
+      }
       $qh_dbh->{InactiveDestroy}  = 1;  # Don't die on fork().
 
       my @hdb_tbl = @{$history_dsn}{qw(D t)};