monitor: fix debug print compiling error

error: 'i' undeclared (first use in this function)

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
exec: file_ram_alloc(): print error when prealloc fails

If memory allocation fails when using the -mem-prealloc command-line
option, QEMU exits without printing any error information to
the user:

 # qemu [...] -m 1G -mem-prealloc -mem-path /dev/hugepages
 # echo $?
 1

This commit adds an error message, so that we print instead:

 # qemu [...] -m 1G -mem-prealloc -mem-path /dev/hugepages
 qemu: unable to map backing store for hugepages: Cannot allocate memory

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Merge remote-tracking branch 'remotes/qmp-unstable/queue/qmp' into staging

* remotes/qmp-unstable/queue/qmp:
  exec: file_ram_alloc(): print error when prealloc fails
  monitor: fix debug print compiling error

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>