perf scripting python: Add missing util/perf_regs.h include to get perf_reg_name() prototype

It was getting it via event.h, that doesn't need that include anymore
and will drop it.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/scripting-engines/trace-event-python.c

@@ -52,6 +52,7 @@
 #include "print_binary.h"
 #include "stat.h"
 #include "mem-events.h"
+#include "util/perf_regs.h"
 
 #if PY_MAJOR_VERSION < 3
 #define _PyUnicode_FromString(arg) \