Consolidate error reporting to make sure that error messages are used
consistently. In addition, don't call `zg_exit()` directly, but instead
return the value 1 in `main()`.
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Acked-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>