exec: split file_ram_alloc()

Move file opening part in a seperate function, file_ram_open(). This
allows for reuse of file_ram_alloc() with a given fd.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170602141229.15326-3-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed