libcamera/base: Introduce new base library

The libcamera-base.so will feature internal support functionality
that is utilised by libcamera, and can be shared in other places.

This new library provides a layer beneath libcamera which provides
common abstractions to internal objects.

A pkg-config file is generated and named libcamera-base.pc which allows
components such as external IPA modules to link directly to this library
if they need. Normal applications will reference this library through
the Requires: statement provided by the libcamera.pc package
configuration, and linkage will be handled automatically through the
pkg-config mechanisms.

No code is moved to this library yet, this patch only introduces the
framework, construction and linkage.

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/base/meson.build

@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: CC0-1.0
+
+libcamera_base_include_dir = libcamera_include_dir / 'base'
+
+libcamera_base_headers = files([
+])
+
+install_headers(libcamera_base_headers,
+                subdir: libcamera_base_include_dir)

include/libcamera/meson.build

@@ -23,6 +23,7 @@ libcamera_public_headers = files([
 
 include_dir = libcamera_include_dir / 'libcamera'
 
+subdir('base')
 subdir('internal')
 subdir('ipa')