target-ppc: add stubs for KVM breakpoints

target-ppc: add stubs for KVM breakpoints

The latest update to v3.13-rc3 (bf63839f) breaks the
ppc build with KVM:

kvm-all.o: In function `kvm_update_guest_debug':
kvm-all.c:1910: undefined reference to `kvm_arch_update_guest_debug'
kvm-all.o: In function `kvm_insert_breakpoint':
kvm-all.c:1937: undefined reference to `kvm_arch_insert_sw_breakpoint'
kvm-all.c:1945: undefined reference to `kvm_arch_insert_hw_breakpoint'
kvm-all.o: In function `kvm_remove_breakpoint':
kvm-all.c:1977: undefined reference to `kvm_arch_remove_sw_breakpoint'
kvm-all.c:1985: undefined reference to `kvm_arch_remove_hw_breakpoint'
kvm-all.o: In function `kvm_remove_all_breakpoints':
kvm-all.c:2009: undefined reference to `kvm_arch_remove_sw_breakpoint'
kvm-all.c:2006: undefined reference to `kvm_arch_remove_sw_breakpoint'
kvm-all.c:2017: undefined reference to `kvm_arch_remove_all_hw_breakpoints'

We need stubs until something gets implemented.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Alexander Graf <agraf@suse.de>