[POWERPC] Switch to using user_regset-based core dumps

This switches powerpc to using the user_regset-based code for ELF core
dumps.  The core dumps come out exactly the same either way, except that
the NT_PPC_VMX note is now omitted for any thread that never touched its
Altivec registers (thread_struct.vr_used).

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/elf.h b/include/asm-powerpc/elf.h
index 6bd07ef..fd9bf8b 100644
--- a/include/asm-powerpc/elf.h
+++ b/include/asm-powerpc/elf.h
@@ -167,6 +167,7 @@
 #define elf_check_arch(x) ((x)->e_machine == ELF_ARCH)
 
 #define USE_ELF_CORE_DUMP
+#define CORE_DUMP_USE_REGSET
 #define ELF_EXEC_PAGESIZE	PAGE_SIZE
 
 /* This is the location that an ET_DYN program is loaded if exec'ed.  Typical