perf tools: Move event synthesizing routines to separate header

Those are the only routines using the perf_event__handler_t typedef and
are all related, so move to a separate header to reduce the header
dependency tree, lots of places were getting event.h and even stdio.h,
limits.h indirectly, so fix those as well.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-yvx9u1mf7baq6cu1abfhbqgs@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/machine.c

@@ -20,6 +20,7 @@
 #include "symbol.h"
 #include "sort.h"
 #include "strlist.h"
+#include "util/synthetic-events.h"
 #include "target.h"
 #include "thread.h"
 #include "util.h"
@@ -2624,6 +2625,15 @@ int __machine__synthesize_threads(struct machine *machine, struct perf_tool *too
 	return 0;
 }
 
+int machine__synthesize_threads(struct machine *machine, struct target *target,
+				struct perf_thread_map *threads, bool data_mmap,
+				unsigned int nr_threads_synthesize)
+{
+	return __machine__synthesize_threads(machine, NULL, target, threads,
+					     perf_event__process, data_mmap,
+					     nr_threads_synthesize);
+}
+
 pid_t machine__get_current_tid(struct machine *machine, int cpu)
 {
 	int nr_cpus = min(machine->env->nr_cpus_online, MAX_NR_CPUS);