kernel 3.17 - perf build failure

[leroy christophe]

   LINK     perf
libperf.a(skip-callchain-idx.o): In function `arch_skip_callchain_idx':
/root/gen/trunk/knl/tools/perf/arch/powerpc/util/skip-callchain-idx.c:250: 
undefined reference to `pr_debug'
libperf.a(skip-callchain-idx.o): In function `check_return_addr':
/root/gen/trunk/knl/tools/perf/arch/powerpc/util/skip-callchain-idx.c:188: 
undefined reference to `pr_debug'
libperf.a(skip-callchain-idx.o): In function `arch_skip_callchain_idx':
/root/gen/trunk/knl/tools/perf/arch/powerpc/util/skip-callchain-idx.c:250: 
undefined reference to `pr_debug'
libperf.a(skip-callchain-idx.o): In function `check_return_addr':
/root/gen/trunk/knl/tools/perf/arch/powerpc/util/skip-callchain-idx.c:165: 
undefined reference to `pr_debug'
/root/gen/trunk/knl/tools/perf/arch/powerpc/util/skip-callchain-idx.c:171: 
undefined reference to `pr_debug'
libperf.a(skip-callchain-idx.o):/root/gen/trunk/knl/tools/perf/arch/powerpc/util/skip-callchain-idx.c:101: 
more undefined references to `pr_debug' follow
collect2: ld returned 1 exit status
make[1]: *** [perf] Error 1
make: *** [install] Error 2