tweak mmap test a bit:
tweak mmap test a bit:

zhihui@lemon: /zzh-s2/zhihui$ cc -o simple simple-mmap.c 
zhihui@lemon: /zzh-s2/zhihui$ ./simple 0
Using private mapping
zhihui@lemon: /zzh-s2/zhihui$ ./simple 1
Using shared mapping
simple: Error mmapping the file.: No such device



git-svn-id: ae92b08b608af1c8cefa3e10d2325ea527204e07@14962 3eda493b-6a19-0410-b2e0-ec8ea4dd8fda

pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable