usage: vercmp <ver1> <ver2>
return values:
< 0 : if ver1 < ver2
0 : if ver1 == ver2
> 0 : if ver1 > ver2
[a...@myarchtp mkarchlive] $ vercmp 0.1 0.1_rc1
-1
[a...@myarchtp mkarchlive] $ vercmp 0.1_rc1 0.1
1
[a...@myarchtp mkarchlive] $ vercmp 0.1_rc1 0.1_r1
1
[a...@myarchtp mkarchlive] $ vercmp 0.1_r1 0.1_rc1
-10.1_rc1 > 0.1 ? 0.1_rc1 > 0.1_r1 ? this is a bug?
