perf tools: Confine __get_cpuid() to x86 architecture

perf tools: Confine __get_cpuid() to x86 architecture

The __get_cpuid() test is only valid when compiling for x86.  When
compiling for other architectures like ARM/ARM64 the test fails event if
the functionality is not required.

This patch isolate the build-in feature check to x86 platform, allowing
the compilation and usage of PMUs that use the AUXTRACE infrastructure
on other architectures (i.e ARM CoreSight).

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1474041004-13956-2-git-send-email-mathieu.poirier@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>