Update s390x config files: Disable CONFIG_WATCHDOG_NOWAYOUT

It's already disabled on all other architectures for a long time and
has been causing problems on s390x (bnc#756585, bnc#895103.)
Update to 3.17-rc5.
- Config changes:
  - NAT config option splitout, no real change:
    - CONFIG_IP6_NF_NAT=m
    - CONFIG_IP_NF_NAT=m
    - CONFIG_NETFILTER_XT_NAT=m
    - CONFIG_NF_NAT_H323=m
    - CONFIG_NF_NAT_IPV4=m
    - CONFIG_NF_NAT_IPV6=m
    - CONFIG_NF_NAT_PPTP=m
    - CONFIG_NF_NAT_PROTO_GRE=m
    - CONFIG_NF_NAT_SNMP_BASIC=m
Update s390x config files: disable CONFIG_EXTCON_SM5502

Enabling CONFIG_EXTCON_SM5502 broke the build, because this option
should depend on CONFIG_I2C which is not enabled on s390x. So disable
CONFIG_EXTCON_SM5502 on s390x, and also disable CONFIG_EXTCON as
there is no point in enabling it when no extcon device driver is
selected.
- Update Xen patches to 3.17-rc5.
- config.conf: Re-enable Xen configs.
- Update config files.
Update EC2 config files (re-enable DEBUG_INFO).
Refresh patches.xen/xen3-patch-3.17-rc5 (fix build issue on native).
supported.conf: i2c-core -> i2core.
Update EC2 config files again (adding DEBUG_INFO_DWARF4).