libsysprof-profiler: start on perf instrument

This starts porting the old perf code from libsysprof into
libsysprof-profile. It does not bring over tracepoints yet, because we
need to think about how we want to support that. I may opt to do that as
a separate instrument even if that takes an additional perf fd.

src/libsysprof-profile/sysprof-sampler.h

@@ -0,0 +1,42 @@
+/* sysprof-sampler.h
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include "sysprof-instrument.h"
+
+G_BEGIN_DECLS
+
+#define SYSPROF_TYPE_SAMPLER         (sysprof_sampler_get_type())
+#define SYSPROF_IS_SAMPLER(obj)      G_TYPE_CHECK_INSTANCE_TYPE(obj, SYSPROF_TYPE_SAMPLER)
+#define SYSPROF_SAMPLER(obj)         G_TYPE_CHECK_INSTANCE_CAST(obj, SYSPROF_TYPE_SAMPLER, SysprofSampler)
+#define SYSPROF_SAMPLER_CLASS(klass) G_TYPE_CHECK_CLASS_CAST(klass, SYSPROF_TYPE_SAMPLER, SysprofSamplerClass)
+
+typedef struct _SysprofSampler      SysprofSampler;
+typedef struct _SysprofSamplerClass SysprofSamplerClass;
+
+SYSPROF_AVAILABLE_IN_ALL
+GType              sysprof_sampler_get_type (void) G_GNUC_CONST;
+SYSPROF_AVAILABLE_IN_ALL
+SysprofInstrument *sysprof_sampler_new      (void);
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (SysprofSampler, g_object_unref)
+
+G_END_DECLS