Glib's g_mapped_file_new maps file with PROT_READ|PROT_WRITE and
MAP_PRIVATE. This leads to premature physical memory allocation of dump
file size on Linux hosts and may fail. On Linux, mapping the file with
MAP_NORESERVE limits the allocation by available memory.

Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20230915170153.10959-5-viktor@daynix.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>