[PATCH] perf arm pmu: fix build error on MUSL libc

[Chanho Park]

Hi Will,
 
> Looks like other files just include this unconditionally, but have a
> comment explaining why. See util/branch.h and util/event.h. Maybe we
> should do the same for util/pmu.h, which is already included here?

I found below files which perf includes <linux/perf_event.h>. Instead of
doing same for all, we'd better put this only for
tools/include/uapi/linux/perf_event.h.

--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -17,6 +17,9 @@
 
 #include <linux/types.h>
 #include <linux/ioctl.h>
+#if !defined(__GLIBC__)
+#include <linux/stddef.h>
+#endif
 #include <asm/byteorder.h>
 
 /*

tools/perf/arch/arm/util/pmu.c:#include <linux/perf_event.h>
tools/perf/arch/x86/util/pmu.c:#include <linux/perf_event.h>
tools/perf/arch/x86/util/tsc.c:#include <linux/perf_event.h>
tools/perf/lib/include/internal/evsel.h:#include <linux/perf_event.h>
tools/perf/lib/include/perf/event.h:#include <linux/perf_event.h>
tools/perf/lib/tests/test-evlist.c:#include <linux/perf_event.h>
tools/perf/lib/tests/test-evsel.c:#include <linux/perf_event.h>
tools/perf/tests/hists_common.c:#include <linux/perf_event.h>
tools/perf/util/auxtrace.c:#include <linux/perf_event.h>
tools/perf/util/auxtrace.h:#include <linux/perf_event.h>
tools/perf/util/branch.h:#include <linux/perf_event.h>
tools/perf/util/event.c:#include <linux/perf_event.h>
tools/perf/util/evsel.c:#include <linux/perf_event.h>
tools/perf/util/evsel.h:#include <linux/perf_event.h>
tools/perf/util/header.h:#include <linux/perf_event.h>
tools/perf/util/mem-events.h:#include <linux/perf_event.h>
tools/perf/util/namespaces.h:#include <linux/perf_event.h>
tools/perf/util/record.h:#include <linux/perf_event.h>
tools/perf/util/session.h:#include <linux/perf_event.h>
tools/perf/util/pmu.h:#include <linux/perf_event.h>
tools/perf/util/synthetic-events.c:#include <linux/perf_event.h>
tools/perf/util/parse-events.h:#include <linux/perf_event.h>
tools/perf/util/perf_event_attr_fprintf.c:#include <linux/perf_event.h>

Best Regards,
Chanho Park