libcamera: Separate source and build path helpers

The libcameraSourcePath and libcameraBuildPath helper functions are
internal and specific to libcamera needs while operating with the meson
build system.

In preparation for the upcoming move of utils to a common library, move
these helpers out of utils and into their own build unit.

Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Hirokazu Honda<hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/internal/meson.build

@@ -39,6 +39,7 @@ libcamera_internal_headers = files([
     'process.h',
     'pub_key.h',
     'semaphore.h',
+    'source_paths.h',
     'sysfs.h',
     'thread.h',
     'timer.h',

include/libcamera/internal/source_paths.h

@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * source_paths.h - Identify libcamera source and build paths
+ */
+#ifndef __LIBCAMERA_INTERNAL_SOURCE_PATHS_H__
+#define __LIBCAMERA_INTERNAL_SOURCE_PATHS_H__
+
+#include <string>
+
+namespace libcamera::utils {
+
+std::string libcameraBuildPath();
+std::string libcameraSourcePath();
+
+} /* namespace libcamera::utils */
+
+#endif /* __LIBCAMERA_INTERNAL_SOURCE_PATHS_H__ */