build: Clean up file names variables

The build system defines two variables, public_api and sources, that
store the names of the public headers and the source files respectively.
These files will need to be referenced when generating documentation
from source code, so let's make the variable names more descriptive:

- Rename public_api to libcamera_api and use the files() function
- Rename sources to libcamera_sources
- Add a libcamera_headers variable to hold the internal headers

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/meson.build

@@ -1,6 +1,6 @@
-public_api = [
+libcamera_api = files([
     'libcamera.h',
-]
+])
 
-install_headers(public_api,
+install_headers(libcamera_api,
                 subdir : 'libcamera')

src/libcamera/meson.build

@@ -1,14 +1,19 @@
-sources = files([
+libcamera_sources = files([
     'log.cpp',
     'main.cpp',
 ])
 
+libcamera_headers = files([
+    'include/log.h',
+    'include/utils.h',
+])
+
 includes = [
     libcamera_includes,
     include_directories('include'),
 ]
 
 libcamera = shared_library('camera',
-                           sources,
+                           libcamera_sources,
                            install : true,
                            include_directories : includes)