The 'mon' argument validity is checked in the QEMU_CHECK_MONITOR for the
following functions, so they don't need the NONNULL on their prototype:

qemuMonitorUpdateVideoMemorySize
qemuMonitorUpdateVideoVram64Size
qemuMonitorGetAllBlockStatsInfo
qemuMonitorBlockStatsUpdateCapacity
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>