I can never remember which retval means which thing. This only prints if
-v/--verbose is specified.
Examples:
```
$ ./bin/xbps-uhelper/xbps-uhelper -v cmpver 1 2 ; echo ret: $?
1 < 2
ret: 255
$ ./bin/xbps-uhelper/xbps-uhelper -v cmpver 1 1 ; echo ret: $?
1 = 1
ret: 0
$ ./bin/xbps-uhelper/xbps-uhelper -v cmpver 2 1 ; echo ret: $?
2 > 1
ret: 1
$ ./bin/xbps-uhelper/xbps-uhelper -v pkgmatch 'foo-1.0_1' 'foo>=0' ; echo ret: $?
foo-1.0_1 matches foo>=0
ret: 1
$ ./bin/xbps-uhelper/xbps-uhelper -v pkgmatch 'foo-1.0_1' 'foo<0.1_1' ; echo ret: $?
foo-1.0_1 does not match foo<0.1_1
ret: 0
```
it also seems that getting an error from pkgmatch is currently impossible