error: Use error_reportf_err() where it makes obvious sense

Done with this Coccinelle semantic patch

    @@
    expression FMT, E, S;
    expression list ARGS;
    @@
    -    error_report(FMT, ARGS, error_get_pretty(E));
    +    error_reportf_err(E, FMT/*@@@*/, ARGS);
    (
    -    error_free(E);
    |
	 exit(S);
    |
	 abort();
    )

followed by a replace of '%s"/*@@@*/' by '"' and some line rewrapping,
because I can't figure out how to make Coccinelle transform strings.

We now use the error whole instead of just its message obtained with
error_get_pretty().  This avoids suppressing its hint (see commit
50b7b00), but I can't see how the errors touched in this commit could
come with hints.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1450452927-8346-12-git-send-email-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/qemu-nbd.c b/qemu-nbd.c
index b8be3bc..f9fce4a 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -495,8 +495,8 @@
                                 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF,
                                 &local_err);
             if (local_err) {
-                error_report("Failed to parse detect_zeroes mode: %s",
-                             error_get_pretty(local_err));
+                error_reportf_err(local_err,
+                                  "Failed to parse detect_zeroes mode: ");
                 exit(EXIT_FAILURE);
             }
             if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
@@ -703,8 +703,8 @@
     srcpath = argv[optind];
     blk = blk_new_open("hda", srcpath, NULL, options, flags, &local_err);
     if (!blk) {
-        error_report("Failed to blk_new_open '%s': %s", argv[optind],
-                     error_get_pretty(local_err));
+        error_reportf_err(local_err, "Failed to blk_new_open '%s': ",
+                          argv[optind]);
         exit(EXIT_FAILURE);
     }
     bs = blk_bs(blk);
@@ -719,8 +719,7 @@
                                                    &local_err);
     }
     if (ret < 0) {
-        error_report("Failed to load snapshot: %s",
-                     error_get_pretty(local_err));
+        error_reportf_err(local_err, "Failed to load snapshot: ");
         exit(EXIT_FAILURE);
     }