error: Use error_report_err() where appropriate

Coccinelle semantic patch:

    @@
    expression E;
    @@
    -    error_report("%s", error_get_pretty(E));
    -    error_free(E);
    +    error_report_err(E);
    @@
    expression E, S;
    @@
    -    error_report("%s", error_get_pretty(E));
    +    error_report_err(E);
    (
         exit(S);
    |
         abort();
    )

Trivial manual touch-ups in block/sheepdog.c.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/vl.c b/vl.c
index 8c8f142..1e9aff6 100644
--- a/vl.c
+++ b/vl.c
@@ -2137,8 +2137,7 @@
 
     qemu_chr_new_from_opts(opts, NULL, &local_err);
     if (local_err) {
-        error_report("%s", error_get_pretty(local_err));
-        error_free(local_err);
+        error_report_err(local_err);
         return -1;
     }
     return 0;
@@ -2218,8 +2217,7 @@
 
     opts = qemu_opts_create(qemu_find_opts("mon"), label, 1, &local_err);
     if (!opts) {
-        error_report("%s", error_get_pretty(local_err));
-        error_free(local_err);
+        error_report_err(local_err);
         exit(1);
     }
     qemu_opt_set(opts, "mode", mode);
@@ -3766,7 +3764,7 @@
     os_daemonize();
 
     if (qemu_init_main_loop(&main_loop_err)) {
-        error_report("%s", error_get_pretty(main_loop_err));
+        error_report_err(main_loop_err);
         exit(1);
     }
 
@@ -4033,8 +4031,7 @@
         Error *local_err = NULL;
         qtest_init(qtest_chrdev, qtest_log, &local_err);
         if (local_err) {
-            error_report("%s", error_get_pretty(local_err));
-            error_free(local_err);
+            error_report_err(local_err);
             exit(1);
         }
     }
@@ -4056,7 +4053,7 @@
         if (order) {
             validate_bootdevices(order, &local_err);
             if (local_err) {
-                error_report("%s", error_get_pretty(local_err));
+                error_report_err(local_err);
                 exit(1);
             }
             boot_order = order;
@@ -4066,7 +4063,7 @@
         if (once) {
             validate_bootdevices(once, &local_err);
             if (local_err) {
-                error_report("%s", error_get_pretty(local_err));
+                error_report_err(local_err);
                 exit(1);
             }
             normal_boot_order = g_strdup(boot_order);