zipl: Align struct lowcore to double page size
zipl: Align struct lowcore to double page size

With GCC8 the following warning is displayed:

In file included from cio.h:15,
                 from stage2.h:15,
                 from menu.h:15,
                 from stage2.c:14:
s390.h:193:1: warning: alignment 1 of ‘struct _lowcore’ is less than 8
[-Wpacked-not-aligned]
 } __packed;
 ^

Fix by aligning struct _lowcore to double page size.

Signed-off-by: Jan Höppner <96138615ab4af0813785fa10d283f3d37eca3b78@linux.ibm.com>

ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools