perf kvm stat: Replace kvm-stat.h includes with forward declarations

To reduce the include header dependency tree and speed up perf builds.

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-dngwaxuhfnhksawgdpo6e74n@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/powerpc/util/kvm-stat.c

@@ -3,6 +3,7 @@
 #include "util/kvm-stat.h"
 #include "util/parse-events.h"
 #include "util/debug.h"
+#include "util/evsel.h"
 
 #include "book3s_hv_exits.h"
 #include "book3s_hcalls.h"

tools/perf/arch/s390/util/kvm-stat.c

@@ -11,6 +11,7 @@
 
 #include <errno.h>
 #include "../../util/kvm-stat.h"
+#include "../../util/evsel.h"
 #include <asm/sie.h>
 
 define_exit_reasons_table(sie_exit_reasons, sie_intercept_code);

tools/perf/arch/x86/util/kvm-stat.c

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <errno.h>
 #include "../../util/kvm-stat.h"
+#include "../../util/evsel.h"
 #include <asm/svm.h>
 #include <asm/vmx.h>
 #include <asm/kvm.h>

tools/perf/util/kvm-stat.h

@@ -3,12 +3,13 @@
 #define __PERF_KVM_STAT_H
 
 #include "../perf.h"
-#include "evsel.h"
-#include "evlist.h"
-#include "session.h"
 #include "tool.h"
 #include "stat.h"
 
+struct perf_evsel;
+struct perf_evlist;
+struct perf_session;
+
 struct event_key {
 	#define INVALID_KEY     (~0ULL)
 	u64 key;