[arch] rebuild pacman database

[Xiaoyu Peng]

Hello everyone:

I did a very stupid operation today that i remove the whole
/var/lib/pacman/local :(

I didn't know what would happen untill I found all the
package-dependences have gone.

I have no idea about how to fix it, so turn to the maillist for help.
I really don't want to reinstall my Arch because it has been used over
one years with everythig works fine.

Thanks in advance

Best regards